Method for manufacturing porous structure and method for forming pattern

ABSTRACT

A pattern forming material contains a block copolymer or graft copolymer and forms a structure having micro polymer phases, in which, with respect to at least two polymer chains among polymer chains constituting the block copolymer or graft copolymer, the ratio between N/(Nc−No) values of monomer units constituting respective polymer chains is 1.4 or more, where N represents total number of atoms in the monomer unit, Nc represents the number of carbon atoms in the monomer unit, No represents the number of oxygen atoms in the monomer unit.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a material that is capable offorming a pattern of the order of nanometers in a self-organized manneron a substrate, the pattern being utilized as a mask for forming ananopattern excellent in regularity. The present invention also relatesto a material that is capable of forming a bulk structure of the orderof nanometers in a self-organized manner, the structure being utilizedas it is as a nanostructure of high regularity, or utilized as atemplate for forming another nanostructure of high regularity. Thematerial of the present invention is applied for manufacturing amagnetic recording medium for hard disks having a recording density of10 Gbit/inch² or more, an electrochemical cell, a solar cell, aphotovoltaic device, a light emitting device, a display, a lightmodulating device, an organic FET device, a capacitor, a high-precisionfilter, etc.

[0002] Needs for a fine pattern or structure are increasingly desired,as improvement in performance of electronic parts. In the electronicparts such as LSI and liquid crystal display, for example,micro-fabrication techniques are required. Many devices such as anelectric cell and a capacitor are required small volume and largesurface area. In future, a high-density three-dimensional packaging willbe needed. Lithography is employed in these processes, and thus themanufacturing cost becomes higher as more micro-fabrications are needed.

[0003] On the other hand, there is a technical field where precision ashigh as in the case of the lithography is not needed, although apatterning of the order of nanometers is required. However, a simplepatterning method has not known hitherto, there is no other choice toform a fine pattern by lithography using an electronic beam or deepultraviolet ray in such a technical field. As mentioned above, in thelithography technique, operations are complicated and enormousinvestment is required as the processing dimension becomes smaller.

[0004] Under these circumstances, as a simple pattern forming methodalternative to the lithography technique, a method utilizing a structurehaving micro polymer phases formed in a self-developed manner from ablock copolymer.

[0005] For example, P. Mansky et al. have reported, in Appl. Phys.Lett., Vol. 68, No. 18, p.2586-2588, a method in that a sea-island typemicrophase-separated film made of a block copolymer of polystyrene andpolyisoprene is formed on a substrate, the polyisoprene is decomposed byozonation and removed to form a porous film, and the substrate is etchedusing the porous film as a mask, thereby forming a pattern, to which thestructure having micro polymer phases is transferred, on the substrate.In addition, M. Park et al. have reported, in Science, Vol. 276,1401-1406, a method in that a sea-island type microphase-separated filmmade of a block copolymer of polystyrene and polyisoprene is formed on asubstrate, the polyisoprene phase is doped with osmium oxide by a vaporphase reaction to improve etch resistance, and a pattern is formed usingthe polyisoprene phase selectively doped with osmium oxide as a mask.

[0006] Such a method using the microphase separation of the blockcopolymer is simple and inexpensive as compared with the lithographytechnique. However, the ozonation is complicated as well as needsrelatively long reaction time, so that it is difficult to improvethroughput. Also, since the osmium oxide has high level of toxicity, itis scarcely used in general purpose from the viewpoint of safety.

BRIEF SUMMARY OF THE INVENTION

[0007] An object of the present invention is to provide a patternforming material and a method for forming a pattern, which show highprocess throughput and capable of forming very easily a planar patternor three-dimensional structure of the order of nanometers havingconsiderable regularity.

[0008] A still another object of the present invention is to provide amethod for manufacturing easily a magnetic recording medium, a fieldemission display, a field emission cathode, a separator and electrodefor an electrochemical cell, a catalytic electrode for a fuel cell, afilter, etc., by making use of the aforementioned material.

[0009] A pattern forming material according to the present inventioncomprises a block copolymer or graft copolymer having two polymer chainswhose ratio between N/(Nc−No) values of respective monomer units is 1.4or more, where N represents total number of atoms in the monomer unit,Nc represents the number of carbon atoms in the monomer unit, Norepresents the number of oxygen atoms in the monomer unit.

[0010] The block copolymer or graft copolymer satisfies the conditionsis typically that having a polymer chain containing aromatic rings andan acrylic polymer chain.

[0011] A pattern forming material of the present invention contains ablock copolymer or graft copolymer having a polysilane chain and acarbon-based organic polymer chain.

[0012] A method for forming a pattern of the present invention comprisessteps of: forming a molded product made of an above-mentioned patternforming material; forming a structure having micro polymer phases in themolded product; and dry-etching the molded product to remove selectivelya polymer phase from the structure having micro polymer phases, therebyforming a porous structure.

[0013] A method for forming a pattern of the present invention comprisessteps of: forming a film made of an above-mentioned pattern formingmaterial on a substrate; forming a structure having micro polymer phasesin the film; selectively removing a polymer phase from the structurehaving micro polymer phases formed in the film by dry-etching; andetching the substrate using remaining another polymer phase as a mask,thereby transferring the structure having micro polymer phases to thesubstrate.

[0014] A method for forming a pattern of the present invention comprisessteps of: forming a pattern transfer film on a substrate; forming a filmmade of a pattern forming material comprising a block copolymer or graftcopolymer having two polymer chains whose ratio between dry etch ratesis 1.3 or more on the pattern transfer film; forming a structure havingmicro polymer phases in the film; selectively removing a polymer phasefrom the structure having micro polymer phases formed in the film bydry-etching; etching the pattern transfer film using remaining anotherpolymer phase as a mask, thereby transferring the structure having micropolymer phases to the pattern transfer film; and etching the substrateusing the pattern transfer film as a mask to which the structure havingmicro polymer phases is transferred, thereby transferring the structurehaving micro polymer phases to the substrate.

[0015] Another pattern forming material of the present inventioncontains a block copolymer or graft copolymer having a polymer chainwhose main chain is cut by irradiation with an energy beam and anindecomposable polymer chain against irradiation with an energy beam.

[0016] An electron beam is typically used as the energy beam. Thepolymer chain whose main chain is cut by irradiation with the energybeam is typically an acrylic chain substituted by a methyl group orhalogen at α-position or a polysilane chain.

[0017] A method for forming a pattern of the present invention comprisessteps of: forming a molded product made of an above-mentioned patternforming material; forming a structure having micro polymer phases in themolded product; irradiating the molded product with an energy beam,thereby cutting a main chain of a polymer phase in the structure havingmicro polymer phases; and selectively removing the polymer chain whosemain chain is cut by development or etching, thereby forming a porousstructure consisting of remaining another polymer phase.

[0018] A method for forming a pattern of the present invention comprisessteps of: forming a film made of an above-mentioned pattern formingmaterial on a substrate; forming a structure having micro polymer phasesin the film; irradiating the film with an energy beam, thereby cuttingthe main chain of a polymer phase in the structure having micro polymerphases; selectively removing the polymer chain whose main chain is cutfrom the structure having micro polymer phases by etching; and etchingthe substrate using remaining another polymer phase as a mask, therebytransferring the structure having micro polymer phases to the substrate.

[0019] A method for forming a pattern of the present invention comprisessteps of: forming a pattern transfer film on a substrate; forming a filmmade of an above-mentioned pattern forming material on the patterntransfer film; forming a structure having micro polymer phases in thefilm; irradiating the film with an energy beam, thereby cutting the mainchain of a polymer phase in the structure having micro polymer phases;selectively removing the polymer chain whose main chain is cut from thestructure having micro polymer phases by etching; etching the patterntransfer film using remaining another polymer phase as a mask, therebytransferring the pattern of the structure having micro polymer phases tothe pattern transfer film; and etching the substrate using the patterntransfer film to which the pattern of the structure having micro polymerphases is transferred as a mask, thereby transferring the structurehaving micro polymer phases to the substrate.

[0020] A still another pattern forming material of the present inventioncomprises a block copolymer or graft copolymer comprising: a polymerchain comprising a repeating unit represented by the following formula:

[0021] where R¹ and R² independently represent a substituted orunsubstituted alkyl group, aryl group aralkyl group or alkoxyl grouphaving 1 to 20 carbon atoms, and a thermally decomposable polymer chain.

[0022] The thermally decomposable polymer chain is typically apolyethylene oxide chain and a polypropylene oxide chain.

[0023] A method for forming a pattern of the present invention comprisessteps of: forming a film made of a pattern forming material comprising ablock copolymer or graft copolymer having at least one thermallydecomposable polymer chain on a substrate; forming a structure havingmicro polymer phases in the film; removing the thermally decomposablepolymer phase from the structure having micro polymer phases by heatingto a thermal decomposition temperature or more; etching the substrateusing remaining another polymer phase as a mask, thereby transferringthe pattern of the structure having micro polymer phases to thesubstrate.

[0024] A method for forming a pattern of the present invention comprisessteps of: forming a pattern transfer film on a substrate; forming a filmmade of a pattern forming material comprising a block copolymer or graftcopolymer having at least one thermally decomposable polymer chain onthe pattern transfer film; forming a structure having micro polymerphases in the film; removing the thermally decomposable polymer phasefrom the structure having micro polymer phases by heating to a thermaldecomposition temperature or more; etching the pattern transfer filmusing remaining another polymer phase as a mask, thereby transferringthe pattern of the structure having micro polymer phases to the patterntransfer film; etching the substrate using the pattern transfer film asa mask, to which the pattern of the structure having micro polymerphases is transferred, thereby transferring the pattern of the structurehaving micro polymer phases to the substrate.

[0025] A method for forming a pattern of the present invention comprisessteps of: forming a molded product made of a pattern forming materialcomprising a block copolymer or graft copolymer having at least onethermally decomposable polymer chain; forming a structure having micropolymer phases in the molded product; removing the thermallydecomposable polymer phase by heating to a thermal decompositiontemperature or more, thereby forming a porous structure consisting ofremaining another polymer phase; and filling pores of the porousstructure with an inorganic material.

[0026] An electrochemical cell of the present invention comprises a pairof electrodes and a separator interposed between the electrodes andimpregnated with an electrolyte, wherein the separator is constituted bya porous structure formed by selectively removing a polymer phase from ablock copolymer or graft copolymer having a structure having micropolymer phases.

[0027] An electrochemical cell of the present invention comprises a pairof electrodes and an electrolyte layer interposed between theelectrodes, wherein at least a part of the electrodes is constituted bya porous structure formed by selectively removing a polymer phase from ablock copolymer or graft copolymer having a structure having micropolymer phases. The porous structure typically made of carbon.

[0028] A hollow fiber filter of the present invention is made of aporous structure formed by selectively removing a polymer phase from ablock copolymer or graft copolymer having a structure having micropolymer phases.

[0029] A method for manufacturing a porous carbon structure of thepresent invention comprises steps of: mixing a precursor ofthermosetting resin, a surfactant, water and oil, thereby preparing amicroemulsion in which colloidal particles containing the precursor ofthermosetting resin are dispersed; curing the precursor of thermosettingresin unevenly distributed in the colloidal particles; removing thesurfactant, water and oil from the colloidal particles, therebyproviding porous structures of cured thermosetting resin; firing tocarbonize the porous structures.

[0030] A still another method for forming a pattern of the presentinvention comprises steps of: applying a blend of a polymer including ametal particle and a block copolymer or graft copolymer to a substrateto form a film; forming a structure having micro polymer phases in thefilm and segregating the metal particles covered with the polymer in acentral portion of a polymer phase or at an interface between thepolymer phases in the block copolymer or the graft copolymer;selectively or entirely removing the polymer phases by etching in whichthe metal particles are segregated, thereby leaving the metal particles.

[0031] The method is suitably applicable to magnetic recording medium bydepositing a magnetic material on the remaining metal particles. Also,the method is suitable applicable to manufacture of a field emission bydepositing a conductor or semiconductor on the remained metal particlesto form emitters.

[0032] A method for manufacturing a capacitor of the present inventioncomprises steps of: forming a film made of a blend of a polymerincluding a metal particle and a block copolymer or graft copolymer;allowing the film to form a lamella structure having micro polymerphases and segregating the metal particles covered with the polymer in acentral portion of each polymer phase in the lamella structure; andaggregating the metal particles to form a metal layer in the centralportion of each polymer phase in the lamella structure.

[0033] A method for manufacturing a catalytic layer of a fuel cell ofthe present invention comprises steps of: forming a film made of a blendof a block copolymer or graft copolymer including a metal particle and ablock copolymer or graft copolymer; forming a structure having micropolymer phases in the film and segregating the metal particles coveredwith the polymer at an interface between the polymer phases forming thestructure having micro polymer phases; and selectively removing apolymer phase in the structure having micro polymer phases, therebyleaving the metal particles on a surface of remaining another polymerphase.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0034]FIGS. 1A and 1B are atomic force micrographs (AFM) showingexamples of structures having micro polymer phases of the blockcopolymers according to the present invention;

[0035]FIGS. 2A to 2D are diagrammatic views showing examples ofstructures having micro polymer phases of the block copolymers accordingto the present invention;

[0036]FIG. 3 is a graph showing the relationship between N/(Nc−No) valueand dry etch rate of various polymers;

[0037]FIGS. 4A to 4C are cross-sectional views showing a method ofmanufacturing the magnetic recording medium of the present invention;

[0038]FIG. 5 is a cross-sectional view of an electrochemical cellaccording to the present invention;

[0039]FIG. 6 is a cross-sectional view of another electrochemical cellaccording to the present invention;

[0040]FIG. 7 is a cross-sectional view of a direct methanol fuel cellaccording to the present invention;

[0041]FIGS. 8A to 8C are schematic views showing a method ofmanufacturing the capacitor according to the present invention;

[0042]FIG. 9 is a cross-sectional view of a field emission displayaccording to the present invention;

[0043]FIG. 10 is a cross-sectional view of another field emissiondisplay according to the present invention;

[0044]FIG. 11 is an SEM micrograph of a carbon structure manufactured inthe present invention;

[0045]FIG. 12 is an SEM micrograph of a carbon structure manufactured inthe present invention; and

[0046]FIG. 13 is a perspective view showing a catalytic layer of a fuelcell according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0047] Hereinafter, the present invention will be described in moredetail.

[0048] The principle of the present invention is that a film or abulk-molded product of a block copolymer or graft copolymer is formed,which copolymer is allowed microphase-separation, and then a polymerphase is selectively removed, thereby forming a porous film or porousstructure having a pattern of the order of nanometers. The resultantporous film can be used for a mask for etching an underlayer to transferthe pattern. Also, the porous structure can be used as it is for variousapplications as well as can be used for a template for forming anotherporous structure. In the present invention, a difference in dry etchrates, decomposition properties against an energy beam or thermaldecomposition properties between two polymer phases is used in order toremove selectively a polymer phase from a structure having micro polymerphases. Since it is not necessary to use a lithography technique, highthroughput and reduced cost can be obtained.

[0049] First, the block copolymer and graft copolymer will be described.The block copolymer means a linear copolymer in which homopolymer chainsare bonded together in a form of blocks. A typical example of the blockcopolymer is an A-B type block copolymer in which an A polymer chainhaving a repeating unit A and a B polymer chain having a repeating unitB are connected each other and having a structure of:-(AA--AA)-(BB--BB)-. It is possible to employ a block copolymer in whichthree of more kinds of polymer chains are bonded together. In the caseof a triblock copolymer, any of A-B-A type, B-A-B type and A-B-C typecan be employed. A star type block copolymer in which one or more kindsof polymer chains extend radialy from a central portion can be employed.A block copolymer of (A-B)n type or (A-B-A)n type having four or moreblocks can be employed. The graft copolymer has a structure comprising apolymer main chain and another pendent polymer chains as side chains. Inthe graft copolymer, plural kinds of polymers may be pendant as sidechains. Also, a combination of a block copolymer and a graft copolymercomprising a block copolymer, such as A-B type, A-B-A type and B-A-Btype, and pendent polymer chains C can be employed.

[0050] The block copolymer is preferable compared to the graft copolymerbecause a polymer having a narrow molecular weight distribution can beeasily obtained and its composition ratio is also easily controlled.Note that, in the following description, the block copolymer will bemainly described, though the description concerning the block copolymeris applicable as it is to the graft copolymer.

[0051] The block copolymer and graft copolymer can be synthesized byvarious polymerization methods. The most preferable method is a livingpolymerization method. In the living anion polymerization or livingcation polymerization methods, the polymerization of a monomer isinitiated with a polymerization initiator capable of generating an anionor an cation, and then another monomer is successively added thereto,thus a block copolymer can be synthesized. A monomer having a doublebond such as vinyl compound or butadiene, a cyclic ether monomer such asethylene oxide, or a cyclic oligosiloxane monomer can be used as amonomer. It is also possible to use a living radical polymerizationmethod. According to the living polymerization method, the molecularweight and copolymer ratio can be precisely controlled, thus making itpossible to synthesize a block copolymer having a narrow molecularweight distribution. In the case where the living polymerization isemployed, it is preferable to dry sufficiently a solvent with adesiccant such as metal sodium and to prevent oxygen from mixing theretousing a method of freeze drying or bubbling of an inert gas. Thepolymerization reaction is preferably carried out under flow of an inertgas and under a pressurized condition of preferably two atm or more. Thepressurized condition is preferred because contamination of water andoxygen from outside the reaction vessel can be prevented effectively aswell as reaction process can be performed in relatively low cost.

[0052] A block copolymer and graft copolymer can also be synthesized bya reaction between macromers such as telechelic polymers or bypolymerizing a different type of monomer from a macromer terminal as apolymerization initiation point. By making use of a reactive processingmethod, a block copolymer and graft copolymer can also be synthesized insitu by advancing the above reaction in the process of forming astructure having micro polymer phases. For example, an A polymer, inwhich reactive terminal groups or side chain groups are introduced, anda B monomer are mixed, and then the monomer is polymerized by a methodsuch as heating, light irradiation and addition of a catalyst in theprocess of forming a structure having micro polymer phases, thus a blockor graft copolymer comprising a polymer A and polymer B can besynthesized. In addition, a block or graft copolymer can be synthesizedin situ even by a method in which two or more kinds of telechelicpolymers each having a complementary bonding group at the ends or sidechains are blended.

[0053] It is preferable for a chemical bond linking the polymer chainswith each other to be a covalent bond from a viewpoint of bond strength,and particularly preferable to be a carbon-carbon bond or acarbon-silicon bond.

[0054] Since special equipment and skill are required in the synthesismethods of a block copolymer or a graft copolymer as compared with thegeneral radical polymerization, these methods have been mainly adoptedin a research laboratory level, and therefore, the industrialapplications thereof have been very limited in view of cost. However, inthe technical fields such as an electronic industry where highlyvalue-added products are manufactured, a sufficient cost effectivenesscan be obtained even if a block copolymer or a graft copolymer isemployed.

[0055] The block copolymer and graft copolymer, unlike a randomcopolymer, can form a structure, i.e., a structure having micro polymerphases, in which an A phase consisting of aggregated A polymer chainsare spatially separated from a B phase consisting of aggregated Bpolymer chains. In a phase separation given by a general polymer, i.e.,a macrophase separation, since two polymer chains can be completelyseparated to each other, thus ultimately two phases are completelyseparated. Also, the scale of fluctuation generation is 1 μm or so, thesize of a unit cell is 1 μm or more. On the contrary, the size of a unitcell in the microphase separation given by a block copolymer of graftcopolymer is not made larger than the size of a molecular chain, whichis in the order of several nanometers or several tens nanometers. Inaddition, the structure having micro polymer phases exhibits morphologyin which fine unit cells are very regularly arrayed.

[0056] Various types of morphology of the structure having micro polymerphases will be described. FIGS. 1A and 1B are microphotographs with anatomic force microscope (AMF) of a polystyrene (PS)-polymethacrylate(PMMA) block copolymer, which show plan views of structures having micropolymer phases. FIG. 1A is referred to as a dot structure or asea-island structure, whereas FIG. 1B is referred to as a worm-likestructure. FIGS. 2A to 2D show schematic views of the structures havingmicro polymer phases viewed stereoscopically. FIG. 2A is referred to asa sea-island structure in which another phases are sphericallydistributed in one phase. FIG. 2B is referred to as a cylindricalstructure in which another phases in a rod-like form are regularlydistributed in one phase. FIG. 2C is referred to as a bicontinuousstructure. FIG. 2D is referred to as a lamella structure in which Aphases and B phases are alternately and regularly laminated.

[0057] The structure having micro polymer phases of a block copolymer orgraft copolymer can be formed in the following manner. For example, ablock copolymer or graft copolymer is dissolved in a suitable solvent toprepare a coating solution, which is applied to a substrate to form afilm. The film is annealed at a temperature above a glass transitiontemperature of the polymers, thus a favorable phase-separated structurecan be formed. It is also possible to use a method that a copolymer ismelted and annealed at a temperature in the range between above theglass transition temperature and below the phase transition temperatureto allow the copolymer to form a structure having micro polymer phases,and the structure having micro polymer phases is fixed at roomtemperature. A structure having micro polymer phases can also be formedby slowly casting a solution of a copolymer. A structure having micropolymer phases can also be formed by a method that a copolymer is meltedand molded into a desired shape by a hot press molding, an injectionmolding and a transfer molding, etc., followed by annealing.

[0058] According to the Flory-Huggings theory, it is required for thephase separation between an A polymer and B polymer that the free energyAG of mixing must be positive. If the A polymer and B polymer are hardto be blended and the repulsive force between two polymers is intense, aphase separation easily occurs. In addition, the microphase separationeasily occurs as a degree of polymerization of the block copolymerbecomes large, and therefore, there is a lower limit in the molecularweight. However, polymers of respective phases forming thephase-separated structure are not necessarily incompatible with eachother. As long as the precursor polymers of these polymers areincompatible with each other, the structure having micro polymer phasescan be formed. After a phase-separated structure is formed by use of theprecursor polymers, the precursor polymers can be reacted by heating,light irradiation or addition of a catalyst to be converted into desiredpolymers. When the reaction conditions are suitably selected at thattime, the phase-separated structure formed by the precursor polymers isnot destroyed.

[0059] The phase separation is most liable to occur when the compositionratio of an A polymer and B polymer is 50:50. This means that astructure having micro polymer phases that is formed most easily is alamella structure. On the contrary, there may be a case where, even byraising the content of one polymer, it is difficult to form a sea-islandstructure containing small islands consisting of the other polymer.Therefore, the molecular weight of the block copolymer may be animportant factor in order to obtain a desired structure having micropolymer phases.

[0060] However, it is very difficult to polymerize a block copolymerwith precisely controlling the molecular weight. Therefore, it may bepossible to adjust the composition ratio by measuring the molecularweight of the synthesized block copolymer and blending a homopolymer soas to give a desired composition ratio. The addition amount of thehomopolymer is set to 100 parts by weight or less, preferably 50 partsby weight or less, and more preferably 10 parts by weight or less to 100parts by weight of the block copolymer. If the addition amount of thehomopolymer is excessive, there is a possibility to disrupt thestructure having micro polymer phases.

[0061] In addition, if the difference between the solubilities of thetwo polymer constituting the block copolymer is too large, there may beoccur a phase separation between the A-B block copolymer and the Ahomopolymer. In order to avoid the particular phase separation as muchas possible, it is preferable to lower the molecular weight of the Ahomopolymer. This is because the A homopolymer having a low molecularweight increases the negative value of the enthoropy term in theFlory-Huggins equation, making it easy for the A-B block copolymer andthe A homopolymer to be blended together. In addition, the fact that themolecular weight of the A homopolymer is lower than molecular weight ofthe A block in the block copolymer leads to thermodynamic stability.Taking the thermodynamic stability into consideration, it is preferablethat the molecular weight of the A homopolymer is lower than two thirdsof the molecular weight of the A block constituting the block copolymer.On the other hand, if the molecular weight of the A homopolymer islowered to less than 1,000, it may possibly be blended to the B block inthe block copolymer, which is not preferable. In addition, taking theglass transition temperature into consideration, the molecular weight ofthe A homopolymer is more preferably 3,000 or more.

[0062] When a thin film consisting of the pattern forming material ofthe present invention is formed, it is preferable to apply a homogeneoussolution. When the homogeneous solution is used, it is possible toprevent hysteresis during film formation from being remained. If thecoating solution is inhomogeneous as the case where micelles having arelatively large particle size are produced in the solution, it is madedifficult to form a regular pattern due to mixing of an irregularphase-separated structure or it takes a long time to form a regularpattern, which is not preferable.

[0063] The solvent for dissolving the block copolymer should desirablybe a good solvent to two kinds of polymers constituting the blockcopolymer. The repulsive force between polymer chains is proportional toa square of the difference in solubility parameter between two kinds ofpolymer chains. Consequently, when the good solvent to the two polymersis employed, it makes the difference in solubility parameter between twokinds of polymer chains smaller and makes free energy of the systemsmaller, which leads to an advantageous condition for a phaseseparation.

[0064] When a thin film of a block copolymer is intended to form, it ispreferable to employ a solvent having a high boiling point of 150° C. ormore so as to make it possible to prepare a homogeneous solution. When abulk-molded product of a block copolymer is intended to form, it ispreferable to employ a solvent having a low boiling point such as THF,toluene and methylene chloride.

[0065] Examples of pattern forming materials used in the presentinvention will be described hereinafter. First, a pattern formingmaterial consisting of a block copolymer or graft copolymer comprisingtwo or more polymer chains whose difference in dry etch rates is largewill be described. The pattern forming material of the present inventioncomprises a block copolymer or graft copolymer comprising at least twopolymer chains whose ratio between N/(Nc−No) values of respectivemonomer units is 1.4 or more, where N represents total number of atomsin the monomer unit, Nc represents the number of carbon atoms in themonomer unit, No represents the number of oxygen atoms in the monomerunit, and a block copolymer and a graft copolymer comprising apolysilane chain and a carbon-based organic polymer chain. The conditionthat the ratio between N/(Nc−No) values is 1.4 or more with respect totwo polymer chains means the fact that the etching selectivity of eachpolymer chain constituting the structure having micro polymer phases islarge. Namely, when the pattern forming material that meets the abovecondition is allowed to form a structure having micro polymer phases andthen is subjected to dry etching, a polymer phase is selectively etchedand the other polymer phase is left remained.

[0066] The parameter of N/(Nc−No) will be described in detail below. Inthis parameter, N is a total number of atoms per segment (whichcorresponds to monomer unit) of a polymer; Nc is the number of carbonatom; and No is the number of oxygen atom. The parameter is an indexindicating the dry etch resistance of a polymer, in that the etch rateby dry etching is made higher (or the dry etch resistance is lowered) asthe value of the parameter becomes larger. In other words, there is afollowing relationship between the etch rate V_(etch) and theaforementioned parameter.

[0067] V_(etch)∝N/(Nc−No)

[0068] This tendency is scarcely dependent on the types of etching gassuch as Ar, O₂, CF₄, H₂, etc. (J. Electrochem. Soc., 130, 143(1983)). Asfor the etching gas, in addition to Ar, O₂, CF₄ and H₂ that aredescribed in the above publication, it is also possible to employ C₂F₆,CHF₃, CH₂F₂, CF₃Br, N₂, NF₃, Cl₂, CCl₄, HBr, SF₆, etc. Note that, theparameter has nothing to do with the etching of an inorganic materialsuch as silicon, glass and metal.

[0069] The specific value of the parameter can be calculated byreferring to the following chemical formula. Since the monomer unit ofpolystyrene (PS) is C₈H₈, the parameter is expressed as 16/(8−0)=2.Since the monomer unit of polyisoprene (PI) is C₅H₈, the parameter isexpressed as 13/(5−0)=2.6. Since the monomer unit of polymethacrylate(PMMA) is C₅O₂H₈, the parameter is expressed as 15/(5−2)=5. Therefore,in the block copolymer of PS-PMMA, it is expected that the etchresistance of PS is higher, and only PMMA is likely etched. For example,it has been confirmed that, when the block copolymer is subjected to areactive ion etching (RIE) with flowing CF₄ in a flow rate of 30 sccmand setting the pressure to 0.01 Torr under the conditions of 150 W inprogressive wave and 30 W in reflective wave, PMMA is etched at an etchrate that is 4±0.3 times faster than PS.

[0070]FIG. 3 shows a relationship between the N/(Nc−No) value of eachpolymer and the etch rate thereof. The abbreviations employed in FIG. 3respectively represent the following polymers. SEL-N=(trade name, SomerKogyo Co., Ltd.), PMMA=polymethyl methacrylate, COP=glycidylmethacrylate-methyl acrylate copolymer, CP-3=methacrylate-t-butylmethacrylate copolymer, PB=polybenzyl methacrylate,FBM=polyhexafluorobutyl methacrylate, FPM=polyfluoropropyl methacrylate,PMIPK=polymethyl isopropenyl ketone, PS=polystyrene, CMS=chloromethlatedstyrene, PαMS=poly(α-methylstyrene), PVN=polyvinylnaphthalene,PVB=polyvinylbiphenyl, and CPB=cyclized polybutadiene. As shown in thefigure, it is found that the relationship of V_(etch)∝N/(Nc−No) iseffected.

[0071] In a polymer including an aromatic ring and having many doublebonds, the value of the above parameter becomes smaller in generalbecause the ratio of carbon is relatively increased. As seen from theafore-mentioned parameter, the larger the number of carbon atom in thepolymer (the smaller the value of the parameter), the higher the dryetch resistance, and the larger the number of oxygen atom in the polymer(the larger the value of the parameter), the lower the dry etchresistance. This can be described qualitatively as follows. Namely,carbon is less reactive to radicals, and hence is chemically stable.Therefore, a polymer containing a large number of carbon atoms is hardlyreactive to various kinds of radicals, which leads to improve etchresistance. Whereas oxygen is highly reactive to radicals, so that apolymer having a large number of oxygen atoms is etched at a high etchrate, and thus has low etch resistance. Additionally, when oxygen isincluded in a polymer, oxygen radicals may be easily generated.Therefore, when a fluorine-based etching gas such as CF₄ is employed, Fradicals are multiplied due the effect of oxygen radicals and theradicals taking part in the etching are increased, leading to increasethe etch rate. An acrylic polymer has high oxygen content and a smallnumber of double bonds, which brings about increase in the value of theabove parameter, so that it can be easily etched.

[0072] Therefore, typical block copolymers having a large difference indry etch-rates comprise an aromatic ring-containing polymer chain and anacrylic polymer chain. An example of the aromatic ring-containingpolymer chain includes a polymer chain synthesized by polymerizing atleast one monomer selected from the group consisting of vinylnaphthalene, styrene and derivatives thereof. An example of the acrylicpolymer chain includes a polymer chain synthesized by polymerizing atleast one monomer selected from the group consisting of acrylic acid,methacrylic acid, crotonic acid and derivatives thereof.

[0073] As mentioned above, when the ratio of the N/(Nc−No) parameterbetween the A polymer chain and the B polymer chain constituting thepattern forming material is 1.4 or more, it is possible to obtain aclear pattern etching. When this ratio is 1.5 or more, preferably 2 ormore, it is possible to ensure a large difference in etch rates betweentwo kinds of polymer chain, thereby making it possible to enhance thestability in the processing. It is preferable in the actual dry etchingthat the etching selectivity between two kinds of polymer chains be 1,3or more, more preferably 2 or more, still more preferably 3 or more.When the ratio of the N/(Nc−No) parameter between the A polymer chainand the B polymer chain constituting the pattern forming material is 1.4or more, it is possible to obtain a satisfactory pattern by means ofetching without employing a polymer chain to which a metal element isdoped or a metal element is introduced. Since patterning can beperformed without employing a metal element, the material is very usefulfor manufacturing various electronic devices in which metal impuritiesbring about problems.

[0074] In order to enhance the etching selectivity in the case where O₂gas is employed as an etching gas, it is especially preferable to use asilicon-containing polymer chain as a polymer chain having higher etchresistance and a halogen-containing polymer chain as a polymer chainhaving lower etch resistance. As the silicon-containing polymer chain, asilicon-containing aromatic polymer chain such as poly(p-trimethylsilylstyrene) is preferred. AS the halogen-containing polymer chain, ahalogen-containing acrylic polymer chain such as poly(chloroethylmethacrylate) is preferred.

[0075] Another pattern forming material consisting of a block copolymeror graft copolymer comprising two or more kinds of polymer chains havinglarge difference in etch rates will be described. A pattern formingmaterial of the present invention comprises a block copolymer or graftcopolymer comprising a polysilane chain and a carbon-based organicpolymer chain.

[0076] The block copolymer having a polysilane chain can be synthesizedby copolymerization between a polystyrene-based macromer anddichlorosilane as disclosed by S. Demoustier-Champagne et al (Journal ofPolymer Science: Part A: Polymer Chemistry, Vol. 31, 2009-2014(1993)),or by living polymerization between polysilane using masked disilene andmethacrylates as disclosed by Sakurai et al (Japan Chemical Society,76th Spring Meeting, Preprint I, Lecture No. 4B513). Since polysilane isa silicon-based polymer, which can be dry-etched easier than a generalcarbon-based polymer.

[0077] The polysilane chain employed in the pattern forming material ofthe present invention comprises any one of the repeating unitsrepresented by the following chemical formulas at least partly.

[0078] where R¹, R², R³ and R⁴ respectively represent a substituted orunsubstituted alkyl, aryl or aralkyl group having 1 to 20 carbon atoms.

[0079] The polysilane may be a homopolymer or a random copolymer, or maybe a block copolymer having a structure in which two kinds of polysilaneare linked together via an oxygen atom, a nitrogen atom, an aliphaticgroup or an aromatic group. Examples of the polysilane includepoly(methylphenylsilane), poly(diphenylsilane),poly(methylchloromethylphenylsilane), poly(dihexylsilane),poly(propylmethylsilane), poly(dibutylsilane), and a random and blockcopolymer thereof.

[0080] Next, a pattern forming material utilizing difference indecomposition properties by an energy beam between two or more polymerchains constituting a block copolymer or graft copolymer will bedescribed. The pattern forming material of the present inventioncomprises a block copolymer or graft copolymer comprising a polymerchain whose main chain is cut by irradiation with an energy beam and anindecomposable polymer chain against irradiation with an energy beam.The polymer chain whose main chain has been cut by irradiation with theenergy beam can be removed by means of wet etching such as rinsing witha solvent or by evaporation by heat treatment. Thus, a fine pattern or astructure retaining a structure having micro polymer phases can beformed without a dry etching process. There are some cases depending onthe types of electronic materials where a dry etching process is notapplicable or a wet etching process is more preferable in view ofmanufacturing cost even if a dry etching process is applicable.Therefore, it is very advantageous not to use a dry etching process.

[0081] Since a block copolymer has two or more kinds of polymers linkedthrough a chemical bond, the block copolymer is generally hard to bedeveloped even if one polymer chain represents high solubility to adeveloper. However, when a block copolymer of polystyrene (PS) andpolymethyl methacrylate (PMMA), for example, is irradiated with anelectron beam, the main chain of PMMA is cut, so that only the PMMAphase can be dissolved in the developer. The developer is notparticularly restricted as long as it can selectively dissolve out toremove the decomposed polymer chain, and therefore it may be awater-based solvent or an organic solvent. In the case of PMMA, methylisobutyl ketone (MIBK), ethyl lactate, acetone, etc., can be employed.In order to adjust the solubility of the polymer, other solvent such asisopropyl alcohol (IPA) may be added to the developer as well as asurfactant may be added. Ultrasonic cleaning may be performed duringdevelopment. Since the polymer chain after decomposition is lowered inmolecular weight and can be evaporated by heat treatment, it can beeasily removed.

[0082] At least one polymer constituting a block copolymer or graftcopolymer is cut in the main chain by irradiation with an energy beamsuch as an electron beam, an X-ray, a γ-ray and a heavy particle beam.An electron beam, an X-ray and a γ-ray are preferred since they canpenetrate deep into the molded product of the polymer and advantageousin view of reducing processing cost because of relatively low cost inirradiation equipment. In particular, the electron beam and X-ray aremore preferable, and further the electron beam is most preferablebecause it brings about high efficiency for decomposition of the polymerchain by its irradiation. As an electron beam source, various types ofelectron beam accelerators such as Cockcroft-Walton type, Van de Graafftype, resonance transformer type, insulated-core transformer type, orlinear type, dynamitron type and radio frequency type can be employed.

[0083] The polymer chains decomposed by an energy beam include thosehaving a methyl group at α-position such as polypropylene,polyisobutylene, poly(α-methylstyrene), polymethacrylic acid, polymethylmethacrylate, polymethacrylamide and polymethyl isopropenyl ketone.Also, a polymer chain whose α-position is substituted by a halogen atomexhibits higher decomposition property in main chain. Further,methacrylate polymers whose ester group is substituted by a fluorinatedcarbon or halogenated carbon such as polytrifluoromethyl methacrylate,polytrifluoromethyl-α-acrylate, polytrifluoroethyl methacrylate,polytrifluoroethyl-α-acrylate and polytrichloroethyl-α-acrylate are morepreferable because they exhibit high sensitivity to the energy beam. Inthe case where the energy beam is an X-ray, it is preferable that thepolymer contains a metal element because it brings about improvement indecomposition efficiency.

[0084] The main chain of another at least one polymer chain constitutingthe block copolymer is indecomposable against irradiation with an energybeam. A polymer capable of cross-linking by irradiation with the energybeam is more preferred. As the polymer chain indecomposable againstirradiation with the energy beam, those having a hydrogen atom at theα-position of the polymer chain such as polyethylene, polystyrene,polyacrylic acid, polymethyl acrylate, polyacrylamide and polymethylvinyl ketone are preferred. In addition, a polymer chain having a doublebond such as 1,2-butadiene, which can be cross-linked by the energybeam, may be employed. Further, derivatives of polynorbornene,polycyclohexane, etc., may be employed.

[0085] The electron beam is particularly useful among energy beams forexposure of not only a thin film but also a bulk-molded product. Sincean electron beam exhibits high penetration efficiency to an organicmaterial, in the case, for example, where one of two phases ismethacrylic polymer whose main chain is decomposed by the electron beam,the polymer located inside the bulk is also decomposed. Therefore, whena three-dimensional phase-separated structure is formed by use of ablock copolymer or a graft copolymer, followed by irradiation with theelectron beam and development, regularly arrayed pores of the order ofnanometers can be easily formed with retaining the three-dimensionalstructure. Since such a structure that the regularly arrayed pores areformed has a very large specific surface area, it can be used for aseparator of a polymer battery or a capacitor and for a hollow fiber.

[0086] When a blend polymer of polystyrene (PS) and polymethylmethacrylate (PMMA) is irradiated with an ultraviolet ray, the sidechain methyl groups of PMMA are eliminated and carboxylic acids areformed, bringing about change in polarity, so that only one of thephases can be removed by utilizing difference in polarity. However, evenwhen an ArF excimer laser (193 nm) is employed as a light source andexposure is performed at an exposure dose of 1 J/cm², not more thanabout 1% of the side chain methyl groups are eliminated. When a KrFexcimer laser (248 nm), which has relatively weak energy, is employed asa light source, it is necessary to perform exposure at an exposure doseof about 3.4 J/cm². Further, when an i-line (365 nm) or g-line (436 nm)of mercury bright lines is employed, almost no side chain methyl groupis eliminated. It is sufficient to set the exposure dose to about 10mJ/cm² for exposure to a resist for an ordinary semiconductor, when theArF or KrF excimer laser is employed. Taking these facts intoconsideration, it will be recognized that the aforementioned exposuredose of the ultraviolet ray is very high, which brings about asignificant burden to the apparatus.

[0087] In order to eliminate one polymer phase from the copolymer inwhich two or more kinds of polymer chains are chemically bonded, it ispreferable to cut the main chain of the polymer phase. However, highenergy is required for the ultraviolet ray to cut the polymer mainchain, which fact brings a tendency to cause damage to theindecomposable polymer chain. Therefore, it is very difficult toeliminate one of the phases in the copolymer by irradiation with theultraviolet ray. In addition, since the ultraviolet ray is poor inpenetration efficiency to the polymer, it is not suitable for thepurpose of making a bulk-molded product porous. In particular, a blockcopolymer containing a structure capable of absorbing the ultravioletray such as an aromatic ring impairs the penetration efficiency.Further, since a polymer chain decomposed by the ultraviolet ray in highsensitivity is hard to be polymerized by living polymerization, it isdifficult to control the molecular weight distribution or the molecularweight.

[0088] On the contrary, as described above, an electron beam, an X-rayor a γ-ray is very effective because of high penetration efficiency to amolded product and high selectivity in decomposition reaction as well ashigh decomposition efficiency and low cost. In particular, the electronbeam is most preferable because its irradiation can be performedconveniently and in low cost.

[0089] Although the exposure dose of the electron beam is not particularrestricted, it is preferable to set the exposure dose to 100 Gy-10 MGy,more preferably to 1 kGy-1 MGy, and particularly preferably to 10kGy-200 kGy. If the exposure dose is too small, the decomposable polymerchain cannot be sufficiently decomposed. If the exposure dose becomesexcessive, there is a possibility that the decomposed products of thedecomposable polymer chain may be three-dimensionally cross-linked toform a cured product as well as the indecomposable polymer chain may bedecomposed.

[0090] Although the accelerating voltage for the electron beam differsdepending on the thickness of the polymer molded product, it ispreferable to set the accelerating voltage to about 20 kV-2 MV for athin film having a thickness of 10 nm to several tens micrometers, andto about 500 kV-10 MV for a film having a thickness of 100 μm or moreand a bulk-molded product. The accelerating voltage may be raised if ametallic molded product is included in the polymer molded product andthe electron beam is shielded. Electron beams different in acceleratingvoltage may be applied. Further, the accelerating voltage may be variedduring irradiation with the electron beam.

[0091] Next, a pattern forming material consisting of a block copolymeror graft copolymer comprising a thermally decomposable polymer chainwill be described. As for such a block copolymer or graft copolymer, itis preferable to employ a copolymer synthesized from a thermallydecomposable polymer chain and a heat resistant polymer chain. Thedifference in thermal decomposition temperature between the thermallydecomposable polymer chain and the heat resistant polymer chain is 10°C. or more, preferably 50° C. or more, more preferably 100° C. or more.Here, the thermal decomposition temperature represents a temperaturewhere the weight of the polymer degreases by a half when the polymer isheated at 1 atm under an inert gas flow for 30 minutes.

[0092] It is preferable for the thermally decomposable polymer chainwhose main chain is decomposed by heating. On the other hand, it ispreferable for the heat resistant polymer chain to have a glasstransition temperature above the thermal decomposition temperature ofthe thermally decomposable polymer chain or to be constituted by apolymer that causes a cross-linking reaction or intramolecularcyclization reaction at a temperature below the thermal decompositiontemperature of the thermally decomposable polymer chain and convertsinto a heat-resistant structure such as a three-dimensional cross-linkedstructure or ladder structure.

[0093] Examples of the thermally decomposable polymer chain are apolyether such as polyethylene oxide and polypropylene oxide,poly(α-methylstyrene), an acrylic resin such as polyacrylate andpolymethacrylate, and polyphthalaldehide. Polyethylene oxide,polypropylene oxide, poly(α-methylstyrene) and an acrylic resin areparticularly preferable because they can be obtained by livingpolymerization as a polymer chain having a narrow molecular weightdistribution.

[0094] Examples of a carbon-based polymer chain among the heat resistantpolymer chain include polyacrylonitrile, a polyacrylonitrile derivativesuch as α-halogenated polyacrylonitrile, polyamic acid, polyimide, apolyaniline derivative, a polyparaphenylene derivative, apolycyclohexadiene derivative, polybutadiene, and polyisoprene. It ispreferable that the polymer chain is allowed to form a structure havingmicro polymer phases and then is made infusible by heating in air.Polyvinylidene chloride can also be employed as the heat resistantpolymer chain because it can be made infusible by an appropriate method.In order to enhance to make the polymer infusible, a radical generatoror a cross-linking agent may be added.

[0095] Among the heat resistant polymer chains, polyacrylonitrile and apolycyclohexadiene derivative are preferred because they can be formedinto a block copolymer having a narrow molecular weight distribution byanion polymerization or radical polymerization.

[0096] A block copolymer having a polyacrylonitrile chain can besynthesized by a method of, for example, T. Suzuki et al (PolymerJournal, Vol. 14, No. 6, 431-438(1982)). In this method, a blockcopolymer is synthesized by polymerizing acrylonitrile using apolyether, such as polyethylene oxide whose terminal hydroxyl groups areanionized, as a reaction initiator. A graft copolymer having apolyacrylonitrile chain can be synthesized by radical copolymerizationbetween a macromer such as polyethylene oxide or polypropylene oxidehaving a methacrylate structure or a styrene structure at ends andacrylonitrile. When the polyacrylonitrile chain is subjected to heattreatment at a temperature of 200° C. or more, preferably 400° C. ormore, a pyridine type ladder-like conductive polymer can be produced.

[0097] A block copolymer having a polycyclohexadiene derivative chaincan be synthesized by living polymerization using a cyclohexadienederivative monomer and another monomer forming a thermally decomposablepolymer chain. Further, the polycyclohexadiene derivative is convertedinto polyparaphenylene by heating. The cyclohexadiene derivative monomerand the polycyclohexadiene derivative are represented by the followingchemical formulas.

[0098] where R¹ and R² independently represent a substituted orunsubstituted alkyl group, aryl group, aralkyl group or alkoxyl grouphaving 1 to 20 carbon atoms. Examples of R¹ and R² include a methylgroup, ethyl group, isopropyl group, t-butyl group, phenyl group,methoxymethyl group and methoxyl group.

[0099] As a polycyclohexadiene derivative, a polymer having a cycliccarbonate structure such as that represented by the following chemicalformula is also suitable.

[0100] The polycyclohexadiene derivative linked at the 1- and4-positions, as shown in the above chemical formula, is most preferablebecause cross-linking occurs easily between neighboring polymer chains.However, a polycyclohexadiene derivative having a structure that linkedat the 1- and 2-positions or a structure in which a portion that linkedat the 1- and 2-positions and a portion that linked at the 1- and2-positions coexist can be employed. A combination of the heat resistantpolymer consisting of the polycyclohexadiene derivative polymer chainand the thermally decomposable polymer chain selected from polyethyleneoxide chain and polypropylene oxide chain is preferred.

[0101] A polymer chain having sites at the side chain or the main chainthat is cross-linked to form a heat resistant molecular structure can beemployed as a heat resistant polymer chain. For example, a polymerhaving a perylene skeleton in the side chains or the main chain can besuitable used. Also, a polymer chain having a siloxane cluster such asPOSS (Polyhedral Oligomeric Silsesquioxane: polysiloxane T₈-cube) in theside chains or the main chain can be used. For example, a polymer chainsynthesized from the polysiloxane T₈ cube represented by the followingchemical formula is preferred.

[0102] where R represents H or a substituted or unsubstituted alkylgroup, aryl group or aralkyl group. Specific examples of R include amethyl group, an ethyl group, a butyl group, an isopropyl group and aphenyl group.

[0103] As a heat resistant polymer chain, polybutadiene or polyisoprenesynthesized by polymerizing a monomer having conjugated double bonds,followed by being three-dimensionally cross-linked at the side chain ormain chain with each other, may be used. 1,2-Polybutadien is mostpreferably used as an afore-mentioned cross-linkable polymer. Acopolymer comprising a polybutadiene chain may contain a little amountof 1,4-polybutadiene units besides the 1,2-polybutadien units. However,since the 1,4-polybutadiene unit is poor in cross-linking capability,the content of the unit is preferably 10% or less, more preferably 5% orless based on the total monomer units in the polybutadiene chain.

[0104] A block copolymer or graft copolymer having a polybutadiene chainor polyisoprene chain as a cross-linkable polymer chain and apolyethylene oxide chain or polypropylene oxide chain as a thermallydecomposable polymer chain is preferred.

[0105] These cross-linkable polymer chains are three-dimensionallycross-linked with each other by adding a radical generator orcross-linking agent. The cross-linkable polymer chain such aspolybutadiene is hydrophobic and the polyethylene oxide chain ishydrophilic. Therefore, a radical generator or cross-linking agenthaving relatively high hydrophobicity is preferred because it has a highaffinity to the phase of the cross-linkable polymer chain.

[0106] Typical radical generator is organic peroxide. Examples of theorganic peroxide include ketone peroxide such as methyl ethyl ketoneperoxide, cyclohexanon peroxide, methyl cyclohexanon peroxide, methylacetoacetate peroxide, and acetoacetate peroxide; peroxyketal such as1,1-bis(t-hexylperoxy)-3,3,5-trimethylcyclohexane,1,1-bis(t-hexylperoxy) cyclohexane,1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,di-t-butylperoxy-2-methylcyclohexane, 1,1-bis(t-butylperoxy)cyclohexane,1,1-bis(t-butylperoxy)cyclododecane, 2,2-bis(t-butylperoxy)butane,n-butyl-4,4-bis(t-butylperoxy) valerate, and2,2-bis(4,4-di-t-butylperoxycyclohexyl) propane; hydroperxoide such asp-menthane hydroperxoide, diisopropylbenzene hydroperxoide,1,1,3,3-tetramethybutyl hydroperxoide, cumene hydroperxoide, t-hexylhydroperxoide, and t-butyl hydroperxoide; dialkyl peroxide such asα,α′-bis(t-butylperoxy)diisopropylbenzene, dicumyl peroxide,2,5-dimethyl-2,5-bis(t-butylperoxy)hexane, t-butyl cumyl peroxide,di-t-butyl peroxide, and 2,5-dimethyl-2,5-bis(t-butylperoxy)hexyne;diacyl peroxide such as isobutyryl peroxide, 3,5,5-trimethylhexanoylperoxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide,succinic acid peroxide, m-toluoyl and benzoyl peroxide, and benzoylperoxide; peroxycarbonate such as di-n-propyl peroxydicarbonate,diisopropyl peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, di-2-ethoxyethyl peroxydicarbonate, di-2-ethyhexylperoxydicarbonate, di-3-methoxybutyl peroxydicarbonate, anddi(3-methy-3-methoxybutyl) peroxydicarbonate; peroxy ester such asα,α′-bis(neodecanoylperoxy)diisopropylbenzene, cumyl peroxyneodecanoate,1,1,3,3-tetramethylbutyl peroxyneodecanoate, 1-cyclohexyl-1-methylethylperoxyneodecanoate, t-hexyl peroxyneodecanoate, t-butylperoxyneodecanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate,1,1,3,3-tetramethylbutyl peroxy-2-ethyhexanoate,2,5-dimethy-2,5-bis(2-ethylhexanoylperoxy)hexane,1-cyclohexyl-1-methyethyl peroxy-2-ethylhexanoate, t-hexylperoxy-2-ethylhexanoate, t-butyl peroxy-2-ethylhexanoate, t-butylperoxyisobutyrate, t-hexyl peroxyisopropylmonocarbonate, t-butylperoxymaleic acid, t-butyl peroxy-3,5,5-trimethylhexanoate, t-butylperoxylaurate, 2,5-dimethyl-2,5-(m-toluyl peroxy)hexane, t-butylperoxyisopropylmonocarbonate, t-butyl peroxy-2-etylhexyl monocarbonate,t-hexyl peroxybenzoate, 2,5-dimethyl-2,5-bis(benzoyl peroxy)hexane,t-butyl peroxyacetate, t-butyl peroxy-m-toluylbenzoate, t-butylperoxybenzoate, and bis(t-butyl peroxy)isophthalate; t-butylperoxyallylmonocarbonate, t-butyl trimethylsilyl peroxide,3,3′,4,4′-tetrakis(t-butyl peroxycarbonyl)benzophenone, and2,3-dimethyl-2,3-diphenylbutane. A polyfunctional radical generator suchas 2,2-bis(4,4-di-t-butyl peroxycyclohexyl)propane or3,3′,4,4′-tetra(t-butyl peroxycarbonyl)benzophenone is preferred becauseit also functions as a cross-linking agent. Also, a radical generatorsuch as azobisisobutylonitrile other than peroxide can be employed.

[0107] The addition amount of the radical generator is preferably 0.1 to20 wt %, more preferably 1 to 5 wt % based on the cross-linkable polymerchain. If the amount of the radical generator is too small, density ofthe cross-linkage is decreased, whereas, if the amount of the radicalgenerator is too large, the cross-linked product may be porous or thestructure having micro polymer phases may be disordered.

[0108] In the case where the radical generator is added to a copolymercomprising a cross-linkable polymer chain, it is preferable that thecross-linking reaction is initiated after formation of the structurehaving micro polymer phases has sufficiently advanced. The formation ofthe structure having micro polymer phases occurs at a temperature abovethe glass transition temperature of each polymer chain in the copolymer.Therefore, it is preferable that the glass transition temperature of thepolymer chains is sufficiently lower than the radical generationtemperature of the radical generator.

[0109] From this point of view, preferred is a composition in which2,2-bis(4,4-di-t-butyl peroxycyclohexyl)propane or3,3′,4,4′-tetra(t-butyl peroxycarbonyl)benzophenone is added to a blockcopolymer comprising a 1,2-polybutadiene chain and a polyethylene oxidechain or polypropylene oxide chain by 1 to 5 wt % based on the1,2-polybutadiene chain. The glass transition temperature of1,2-polybutadiene is about 20° C., and the glass transition temperatureof the polyethylene oxide or polypropylene oxide is lower than 0° C.When each of 2,2-bis(4,4-di-t-butyl peroxycyclohexyl)propane and3,3′,4,4′-tetra(t-butyl peroxycarbonyl)benzophenone is heated at a rateof 4° C./min, the thermal decomposition temperatures of the radicalgenerators are 139° C. and 125° C., respectively.

[0110] When the above composition is heated to a temperature betweenroom temperature and 50° C. to form a structure having micro polymerphases and then is slowly heated to a thermal decomposition temperatureof the radical generator, the cross-linkable polymer chains can becross-linked and cured. However, if the temperature is too high, thereis a possibility that the composition reaches the order-disordertransition temperature before sufficient cross-linkage occurs and thusturns into a homogeneous melt. In this case, 3,3′,4,4′-tetra(t-butylperoxycarbonyl)-benzophenone is advantageous because it generatesradicals even when irradiated with an ultraviolet ray, which enablescross-linking at low temperature.

[0111] A block copolymer comprising a polybutadiene chain and anα-methylacrylic polymer chain can also be employed. An example is acomposition in which 2,2-bis(4,4-di-t-butyl peroxycyclohexyl)propane or3,3′,4,4′-tetra(t-butyl peroxycarbonyl)benzophenone is added to a blockcopolymer comprising a 1,2-polybutadiene chain and a polymethylmethacrylate chain by 1 to 5 wt % based on the 1,2-polybutadiene chain.The polymethyl methacrylate has a relatively high glass transitiontemperature of 105° C., but it is decomposed by irradiation with anelectron beam and is likely to evaporate by annealing at relatively lowtemperature. Namely, with respect to the polymethyl methacrylate, athermal decomposition promoting effect can be obtained.

[0112] In addition, when a thick film is formed by evaporating a solventfrom a solution of a block copolymer comprising a polybutadiene chainand a polymethyl methacrylate chain, a preferable structure having micropolymer phases can be formed without annealing. In this case, when thesolvent is evaporated at a temperature sufficiently lower than thethermal decomposition temperature of the radical generator, the advanceof cross-linkage in the cross-linkable polymer chains may not disturbformation of the structure having micro polymer phases. This method canbe used advantageously where a nanostructure is manufactured by forminga thick porous film and filling the pores with metal. The same effectsimilar to that of the polymethyl methacrylate case be obtained even inthe case where poly(α-methylstyrene) is used.

[0113] In the polymethyl methacrylate or poly(α-methylstyrene), theglass transition temperature can be adjusted by a substituent. Forexample, the glass transition temperatures of poly(n-propylmethacrylate) and poly(n-butyl methacrylate) are 35° C. and 25° C.,respectively. Therefore, a copolymer comprising such a polymer chain canbe annealed at low temperature, making it possible to form a goodstructure having micro polymer phases. Poly(α-methylstyrene) substitutedby a butyl group at the 4-position also exhibits a low glass transitiontemperature. Polymethyl methacrylate substituted by an alkyl grouphaving six or more carbon atoms exhibits a lower glass transitiontemperature, but such a polymer likely to cause cross-linking reactionwhen irradiated with an electron beam. Poly(n-propyl methacrylate),poly(n-butyl methacrylate) and poly(s-butyl methacrylate) are preferredbecause they have both a low glass transition temperature and a thermaldecomposition promoting effect by electron beam irradiation.Polymethacrylate substituted by a branched alkyl group such as a2-ethylhexyl group exhibits the thermal decomposition promoting effectby electron beam irradiation although it has many carbon atoms, but itsmonomer is expensive. Taking easiness in availability intoconsideration, poly(n-butyl methacrylate) and poly(s-butyl methacrylate)are most preferred.

[0114] Polyisobutylene or polypropylene can also be used as a polymerchain having both a low glass transition temperature and a thermaldecomposition promoting effect by electron beam irradiation.

[0115] In the case where electron beam irradiation is performed toobtain the thermal decomposition promoting effect, 1,2-butadiene can becross-linked at the same time, the amount of the radical generator canbe decreased, and there is no need to add the radical generator in somecases. When the radical generator is not added, there is no need to usea copolymer having a low glass transition temperature, but there is atendency that the cross-linkage density is decreased. Therefore, it ispreferable, in this case, to add a cross-linking agent.

[0116] Examples of the cross-linking agent include bismaleimide,polyfunctional acrylate, polyfunctional methacrylate, polyfunctionalvinyl compound, and a silicon compound having a Si—H bond. Inparticular, bismaleimide is excellent in terms of heat resistance.Examples of bismaleimide include bis(4-maleimidophenyl)methane,bis(4-maleimidophenyl) ether,2,2′-bis[4-(paraminophenoxy)phenyl]propane, and2,2′-bis[4-(paraminophenoxy)phenyl]hexafluoropropane. The additionamount of the cross-linking agent is preferably 0.1 to 100 wt %, morepreferably 1 to 20 wt % based on the cross-linkable polymer chain. Ifthe addition amount is too small, the cross-linkage density isdecreased, whereas if the addition amount is too large, the structurehaving micro polymer phases is likely to be disturbed.

[0117] A cross-linked product of 1,2-polybutadiene is excellent in heatresistance, electric characteristics such as insulating property,moisture resistance and mechanical characteristics. Therefore, acomposition comprising a copolymer consisting of a 1,2-polybutadienechain and a polyethylene oxide, polypropylene oxide or polymethylmethacrylate chain and a radical generator is suitable for manufacturinga film for pattern formation or a porous structure. A porous materialconsisting of cross-linked polybutadiene is very useful because it canbe used for various filters.

[0118] A polysilane chain can be employed as a precursor of aheat-resistant polymer chain. Chemical formulas, specific examples andsynthesis methods for polysilanes are already described. The polysilanechain is photo-oxidized by irradiation with an ultraviolet ray in air oran oxygen-containing atmosphere. As a result, reactive or cross-linkableradical terminals are generated by elimination of side chains andcutting of main chain and oxygen insertion produces siloxane bonds. Whenfired after the photo-oxidization, a cross-linking reaction mainlyinvolving the siloxane bond occurs, and the polysilane chain istransformed into a structure analogous to the SiO₂ structure. Also, whena polysilane chain or polycarbosilane chain is irradiated with anultraviolet ray under a nonoxygen or low-oxygen atmosphere and thenfired, the polymer chain is converted to silicone carbide (SiC). Theresultant SiO₂ or SiC exhibits high heat resistance.

[0119] An example of a preferable polysilane chain is one having anaromatic substituent and an alkyl group. Such polysilane has a repeatingunit represented by the following chemical formula.

[0120] where R¹ represents a substituted or unsubstituted aromaticsubstituent having 6 to 20 carbon atoms wherein a phenyl group is mostpreferred, and R² represents a substituted or unsubstituted alkyl grouphaving 1 to 6 carbon atoms wherein a methyl group is most preferred.Poly(methylphenylsilane) is particularly preferred because it can beeasily cross-linked through the elimination of the phenyl group byirradiation with ultraviolet ray.

[0121] It is preferable to use a block copolymer consisting of apolysilane chain and a polyethylene oxide or polypropylene oxide chain.Such a block copolymer is applied to a substrate by spin coating to forma film, followed by forming a phase-separated structure, and then thefilm is exposed to an ultraviolet ray, and heated if desired, to advancecross-linking reaction. Further, the film is heated to thermallydecompose to remove the thermally decomposable polymer chain. As aresult, a pattern of a product analogous to SiO₂ or SiC, to which aphase-separated structure is transformed, is formed. Using the patternas a mask, etching processing of the underlayer or plating can beperformed successfully.

[0122] An additive such as a sensitizer, radical generator and acidgenerator, for example, fullerene, 3,3′,4,4′-tetrakis(t-butylperoxycarbonyl)benzophenone and etc., can be added to the copolymerhaving a polysilane chain, if desired.

[0123] A polysiloxane chain can be used as a precursor of a heatresistant polymer chain. The molecular weight distribution of thepolysiloxane chain can be made small by living polymerization of cyclicoligosiloxane. When a polysiloxane chain having alkoxyl groups on theside chains is heated in a presence of an acid catalyst, it producessiloxane bonds accompanied by elimination of alkoxyl groups to bethree-dimensionally cross-linked, which brings about improvement in heatresistance and mechanical characteristics.

[0124] A polysilane chain and polysiloxane chain having hydroxyl groupsor alkoxyl groups on the side chains are transformed into SiO₂ or SiO₂analogues by firing. Such polysilane and polysiloxane have a repeatingunit, for example, represented by the following chemical formulas.

[0125] where R¹ and R² independently represent a hydrogen atom, or asubstituted or unsubstituted alkyl group, aryl group or aralkyl grouphaving 1 to 20 carbon atoms. Specific examples are polysilane such aspoly(di-1-propoxysilane) and poly(di-t-butoxysilane), and polysiloxanesuch as poly(di-1-propoxysiloxane) and poly(di-t-butoxysiloxane).

[0126] When a block copolymer or graft copolymer having a polysilanechain or polysiloxane chain and a thermally decomposable polymer chainsuch as a polyethylene oxide or polypropylene oxide chain is fired, aporous structure consisting of an SiO₂ analogue material, to which aphase-separated structure is transformed, can be formed. Such a porousfilm functions well as a mask. Also, a porous structure can be appliedto various functional members such as a magnetic recording medium and anelectrode material by filling the pores with an inorganic material suchas metal.

[0127] Polyamic acid can be used as a heat resistant polymer chain. Whenpolyamic acid and an amino-terminated polymer are mixed, a carboxylgroup and an amino group forms a salt, thus a graft copolymer having apolyamic acid main chain and pendent amino-terminated polymers isformed. A Kapton precursor can be used as the polyamic acid. As theamino-terminated polymer, polyethylene oxide, polypropylene oxide orpolymethyl methacrylate having an aminopropoxyl group or dimethylaminopropoxyl group as one terminal group and a methoxyl group ordiphenylmethoxyl group as the other terminal group can be employed. Acopolymer consisting of polyamic acid and amino-terminated polypropyleneoxide is particularly preferable because it can be phase-separated well.In this case, varying the molecular weights of the polyamic acid andamino-terminated polymer, respectively, can control the size of domainsin the structure having micro polymer phases. Also, varying the mixingratio of the polyamic acid and amino-terminated polymer can easilychange morphology of the structure having micro polymer phases.

[0128] Examples of suitable combinations of a heat resistant polymerchain and a thermally decomposable polymer chain described aboveinclude: a polyacrylonitrile chain and a polyethylene oxide chain, apolyacrylonitrile chain and a polypropylene oxide chain, apolymethylphenylsilane chain and a polystyrene chain, apolymethylphenylsilane chain and a poly(α-methylstyrene) chain, apolymethylphenylsilane chain and a polymethyl methacrylate chain, apolymethylphenylsilane chain and a polyethylene oxide chain, and apolymethylphenylsilane chain and a polypropylene oxide chain.

[0129] A heat resistant material may be segregated on one polymer phasein a block copolymer or graft copolymer consisting of a hydrophilicpolymer chain and hydrophobic polymer chain. As the heat resistantmaterial, an inorganic heat resistant material or a precursor thereof,or thermosetting resin can be employed. In this case, all of the polymerchains constituting the copolymer may be thermally decomposable. Forexample, in a block copolymer consisting of a polyethylene oxide chainand polypropylene oxide chain, both polymer chains are thermallydecomposable, but the polyethylene oxide chain is hydrophilic and thepolypropylene oxide chain is hydrophobic. When the inorganic heatresistant material or thermosetting resin is blended with the blockcopolymer, it is apt to be distributed unevenly on the hydrophilicpolyethylene oxide chain. When the blend is allowed to form a structurehaving micro polymer phases, followed by heating to thermally decomposeand evaporate the block copolymer, a porous pattern consisting of theinorganic heat resistant material or thermosetting resin, to which thestructure having micro polymer phases is transferred, can be formed.When the porous pattern is used as a mask, high etching selectivity canbe given. In addition, when a porous structure whose pores filled withmetal is used for a magnetic recording medium or an electrode, gooddurability can be given.

[0130] Examples of the inorganic heat resistant material or precursorthereof include a metal oxide gel, a metal alkoxide polymer, a metaloxide precursor, a metal nitride precursor, metal fine particles, ametal salt and a metal complex. Examples of the metal include silicon,titanium, aluminum, zirconium, tungsten, and vanadium. The metal oxidegel can be obtained by hydrolysis of the metal alkoxide. Examples of themetal alkoxide include alkoxysilane such as tetramethoxysilane,tetraethoxysilane, tetraisopropoxysilane, tetraisopropoxyaluminum andtetraisopropoxytitanium, and alkylalkoxysilane such asbutyltriethoxysilane and propyltriethoxyaluminum. An example of themetal alkoxide polymer includes polydiethoxysiloxane. Examples of themetal oxide precursor or metal nitride precursor includepolysilsesquioxane, T-resin such as polyhedral oligomericsilsesquioxane. (POSS), and polysilazane.

[0131] However, the metal oxide gel is poor in storage stability. Inaddition, if the cross-linking density of the metal oxide gel is toohigh, formation of a structure having micro polymer phases of acopolymer is disturbed. Therefore, it is preferable that a solution inwhich a metal oxide gel precursor such as low-molecular weight metalalkoxide or organic metal salt is mixed with a copolymer is applied to asubstrate to form a film, followed by forming a structure having micropolymer phases, and then the precursor is transformed into a metal oxidegel by the action of a catalyst such as an acid.

[0132] Further, it is preferable to use polysilsesquioxane, T-resin orpolysilazane. In particular, the T-resin does not disturb formation of astructure having micro polymer phases, since its curing rate bycross-linking can be controlled by a catalyst. After the structurehaving micro polymer phases is formed, T-resins can bethree-dimensionally cross-linked with each other and cured by thecatalyst. An example of T-resin is represented by the following chemicalformula.

[0133] where R¹ to R⁸ independently represent a hydrogen atom, a halogenatom, a hydroxyl group, a thiol group, an alkoxyl group, a silyloxylgroup or a substituted or unsubstituted alkyl group, alkenyl group,alkynyl group, aryl group or aralkyl group having a 1 to 20 carbonatoms. Specific examples of T-resin are: those having a hydrogen atom,methyl group, hexyl group, vinyl group or dimethylsilyloxyl group as R¹to R⁸, and those having cyclopentyl groups as R¹ to R⁷ and having ahydrogen atom, hydroxyl group, allyl group, 3-chloropropyl group or4-vinylphenyl group as R⁸.

[0134] Examples of polysilsesquioxane include polymethylsilsesquioxane,polymethylhydroxyl silsesquioxane, polyphenylsilsesquioxane,polyphenylmethylsilsesquioxane, polyphenylpropyl silsesquioxane,polyphenylvinylsilsesquioxane, polycyclohexylsilsesquioxane,polycyclopentyl silsesquioxane, polycyclohexylsilsesquioxane T₈-cube andpoly(2-chloroethyl)silsesquioxane.

[0135] In poly(2-bromoethyl)silsesquioxane, a cross-linking reactionproceeds at low temperature as well as the cross-linking can beperformed by irradiation with an ultraviolet ray. Therefore, apolysiloxane-based polymer having a low glass transition temperature isused and a structure having micro polymer phases is formed, and then itcan be cured by UV irradiation. Polyhydroxylsilsesquioxane,polyphenylsilsesquioxane and poly-t-butoxysilsesquioxane can be used inthe similar manner as above.

[0136] Polyphenylsilsesquioxane is mixed with a copolymer, followed byformation of a structure having micro polymer phases, and then it can becross-linked and cured by the action of a curing catalyst. As the curingcatalyst, dibutyltin diacetate, zinc acetate, and zinc 2-ethylhexanoatecan be used. It is preferable to add the curing catalyst in the range of0.1 to 0.5 wt % based on the silsesquioxane. Silsesquioxane is mixedwith a copolymer, followed by formation of a structure having micropolymer phases, and then it can be cross-linked and cured byhydrochloric acid gas or a hydrochloric acid solution.

[0137] Examples of the thermosetting resin include: polyamic acid, epoxyresin, polyamide resin, polysulfide resin, urea-formaldehyde resin,phenol-formaldehyde resin, resorcinol-formaldehyde resin, furan resinsuch as furfuryl alcohol resin, melamine resin, aniline resin,toluenesulfonic amide resin, isocyanate resin, alkyd resin, furfuralresin, polyurethane, resorcinol resin, polycarbodiimide, and a precursorpolymer of polyparaphenylenevinylene. The thermosetting resin ispreferred because it is excellent in storage stability as well as it canbe easily removed by ashing after it is used as a mask. In particular,polyamic acid, urea-formaldehyde resin, phenol-formaldehyde resin,resorcinol-formaldehyde resin, furan resin such as furfuryl alcoholresin and melamine resin are preferred, and polyamic acid is mostpreferable.

[0138] Examples of the hydrophilic polymer chain constituting a blockcopolymer include polyethylene oxide, poly(hydroxymethyl methacrylate),polyacrylic acid, polymethacrylic acid and carboxylate thereof,quarternized polyvinylpyridine, polyvinyl alcohol, andpoly(hydroxystyrene). In particular, polyethylene oxide,poly(hydroxymethyl methacrylate), polyacrylic acid and polymethacrylicacid are preferred.

[0139] Examples of the hydrophobic polymer chain constituting a blockcopolymer include polypropylene oxide, polystyrene,poly(α-methylstyrene), polymethacrylate, polybutadiene, polyisoprene,polysiloxane, fluorine-containing polymer. It is preferable that thesepolymer chains have a low glass transition temperature and are thermallydecomposable so as to be able to form a structure having micro polymerphases before the heat resistance material is cured. In particular,polypropylene oxide, poly(α-methylstyrene) and polymethacrylate, whichare thermally decomposable at low temperature, and polysiloxane such aspolydimethylsiloxane, which has a low glass transition temperature arepreferred, and further polypropylene oxide and polydimethylsiloxane aremost preferable.

[0140] Examples of suitable combinations of polymer chains constitutinga block copolymer or graft copolymer used together with a heatresistance material include: a polyethylene oxide chain and apolypropylene oxide chain, a polyethylene oxide chain and a polymethylmethacrylate chain, a polyethylene oxide chain and apoly(α-methylstyrene) chain, a polyethylene oxide chain and apolystyrene chain, a polyethylene oxide chain and a polyvinylpyridinechain, a poly(hydroxyethyl methacrylate) chain and a polypropylene oxidechain, a poly(hydroxyethyl methacrylate) chain and apoly(α-methylstyrene) chain, a poly(hydroxyethyl methacrylate) chain anda polystyrene chain, a polyacrylic acid chain and a polypropylene oxidechain, a polyacrylic acid chain and a polymethyl methacrylate chain, apolymethacrylic acid chain and a polymethyl methacrylate chain, apolyacrylic acid chain and a polyphenylmethylsiloxane chain, apolyethylene oxide chain and a polydimethylsiloxane chain, apolyethylene oxide chain and a polyphenylmethylsiloxane chain, and apolyethylene oxide chain and a polyvinylmethylsiloxane chain. Amongthese combinations, combinations of the polyethylene oxide chain and thepolypropylene oxide chain, and the polyethylene oxide chain and thepolydimethylsiloxane chain are preferred, and the combination of thepolyethylene oxide chain and the polydimethylsiloxane chain is mostpreferable. For example, a composition in which thermosetting resin suchas polyamic acid is blended with a block copolymer or graft copolymer ofthe polyethylene oxide chain and the polydimethylsiloxane chain can beused well as a composition for forming a pattern.

[0141] The mixing ratio between a heat resistance material and a blockcopolymer or graft copolymer is not particularly restricted. The heatresistance material is preferably used in the range of 1 to 500 parts byweight, more preferably 5 to 100 parts by weight, still more preferably10 to 50 parts by weight relative to 100 parts by weight of blockcopolymer or graft copolymer. If the mixing amount of the heatresistance material is too small, the composition cannot functionsufficiently as a mask. If the mixing amount of the heat resistancematerial is too large, the microphase-separation structure is disturbedand a good pattern cannot be formed.

[0142] A solvent used for preparing a solution of a mixture of acopolymer and a heat resistant material or precursor thereof shoulddesirably be a good solvent to both the copolymer and the heat resistantmaterial or precursor thereof. In particular, it is preferable to use agood solvent, at the same time, to any of polymer chains constitutingthe copolymer. If a solvent extremely poor in solubility to a particularpolymer chain is used, micelles are apt to be formed in the solution. Inthis case, on the occasion of forming a structure having micro polymerphases in a form of a thin film such as a mask for patterning or atemplate film for a magnetic film for a magnetic recording medium, thehysteresis of the micelle structure formed in the solution is leftremained, which makes it difficult to form a good pattern of thestructure having micro polymer phases.

[0143] In order to form a desired structure having micro polymer phasesfrom a block copolymer or graft copolymer, it is preferable to adjustthe composition ratio between the two kinds of polymer chains, asdescribed above. In the case of an A-B diblock copolymer, the morphologyof the structure having micro polymer phases varies depending on thecomposition ratio between the A polymer and the B polymer, asschematically described below. Where the ratio of a minority phase isvery small, the minority phase is aggregated to form spherical domainsinto a sea-island structure. When the composition ratio of two phasesbecomes 7:3, the minority phase forms columnar domains into cylindricalstructure. When the composition ratio of two phases becomes about 1:1,both phases form sheet-like domains that are alternately laminated intoa lamella structure.

[0144] Here, for the A-B diblock copolymer, the phase diagram leanstoward the side of a polymer phase having a larger surface energy, i.e.,having a larger value of solubility parameter. This means that thecomposition where a domain structure such as a lamella, cylinder orsea-island structure is formed is slightly deviated depending on thecombination of two kinds of polymer chains. Specifically, where thesolubility parameters of two kinds of polymers constituting a blockcopolymer differ from each other by about 1 cal^(0.5)/cm^(1.5), anoptimum composition is shifted by about 5% toward the side of thepolymer having a larger solubility parameter relative to theafore-mentioned composition. Further, when a block copolymer is broughtinto contact with a substrate, a polymer exhibiting a smaller surfaceenergy difference tends to be segregated on the substrate side. Forexample, in the case of PS-PMMA type block copolymer, PMMA tends to beprecipitated on the side of the substrate. On the contrary, in the caseof PS-PB (polybutadiene) type block copolymer, PS tends to beprecipitated on the side of the substrate.

[0145] In the case where a thin film of sea-island structure is to beformed, the composition ratio should desirably be set in the vicinity ofthe transition point between the sea-island structure and the worm-likestructure. In this case, although an optimum composition ratio of theblock copolymer cannot be determined in a general way because aninteraction acts between the polymer and the substrate, the optimumcomposition ratio can be estimated in some measure. Namely, where theminority phase is a phase exhibiting smaller surface energy differencerelative to the substrate, the minority phase tends to be segregated onthe side of the substrate, and therefore it is necessary to set thecomposition of the minority phase larger. For example, since PMMA tendsto be segregated on the surface of the substrate in the case of PS-PMMA,it is necessary to set the ratio of PMMA in the copolymer in which PMMAconstitutes the minority phase than the ration of PS in the copolymer inwhich PS constitutes the minority phase. In addition, the sizedistribution of the spheres or cylinders becomes different due to thedifference in surface tension between the two kinds of polymers. Forthat reason too, the optimum composition ratio for forming aphase-separated structure differs between a block copolymer that an Apolymer constitutes the minority phase and a block copolymer that a Bpolymer constitutes the minority phase. For example, assuming that anoptimum composition ratio that the A polymer having an affinity to asubstrate forms dots on the substrate is A:B=20:80, there is a casewhere an optimum composition ratio that the B polymer forms dots on thesurface becomes A:B=85:15. This is because, as a polymer tends to beadsorbed on the substrate, an extra volume of polymer is required in thebulk.

[0146] It is preferable to set the volume fraction of the two polymerphases constituting a block copolymer as follows. For example, where thesea-island structure is to be formed, the volume fraction of one phaseis set to the range of 5 to 40%, preferably 10 to 35%, more preferably15 to 30%. The density of islands governs the lower limit of the volumefraction, while the range where the sea-island structure can bemaintained governs the upper limit. If the volume fraction exceeds theupper limit, another structure such as a cylindrical structure otherthan the sea-island structure is formed. Note that, where a thin filmhaving a thickness of about several tens nanometers is to be formed, theinfluence of the interface becomes significant, the above optimum valueshould be made smaller by 2 to 5%. In order to adjust the volumefraction of the two phases, the copolymerization ratio of the blockcopolymer may be controlled; alternatively the molecular volume of thepolymer chain may be controlled. The control the molecular volume can beachieved by various methods. For example, in the process of quaterize apolyvinyl pyridine chain, the molar volume of an alkyl group or acounter anion may be changed. Alternatively, a substance exhibits a highaffinity to a specific phase may be mixed so as to adjust the volumeratio of the phase. In this case, a homopolymer of a constituent polymerchain of the block copolymer may be employed as the substance to bemixed.

[0147] In order to form a good three-dimensional bicontinuous structure,it is required to be incompatible with each other between an A polymerchain and a B polymer chain; an A polymer chain and a precursor of Bpolymer chain; a precursor of A polymer chain and a B polymer chain; ora precursor of A polymer chain and a precursor of B polymer chain. Wherea precursor is employed, the phase-separated structure is formed, andthen the precursor is subjected to a chemical reaction under atemperature condition lower than the glass transition temperature of thecopolymer to transform into a desired polymer chain. In this case, themolecular weight of each block should preferably be 3,000 or more. Inorder to adjust the composition ratio, a small amount of homopolymer maybe added, if desired, to a solution of the block copolymer having twopolymer chains incompatible with each other.

[0148] Various additives may be added to a solution of a blockcopolymer. As for the additive, it is preferable to use one having aspecifically high affinity to one of the polymer chains to bephase-separated to each other. In this case, the additive can be easilysegregated on the polymer phase having a high affinity in the process offormation of the phase-separated structure. As a result, a phasecontaining the additive can be improved in etch resistance. Inparticular, when the additive is segregated on a heat resistant phase,more excellent patterning can be performed.

[0149] As for the additives, there may be used a metal salt of Cr, V,Nb, Ti, Al, Mo, Li, Lu, Rh, Pb, Pt, Au, Ru, etc., and an organic metalcompound. A metal element produced by reducing such additives can beutilized as a nucleus for a magnetic film of a magnetic recording mediumof an electrode material for an electrochemical cell. Examples of suchadditives include lithium 2,4-pentanedionate, lithiumtetramethylpentanedionate, ruthenium 2,4-pentanedionate, magnesium2,4-pentanedionate, magnesium hexafluoropentanedionate, magnesiumtrifuoropentanedionate, manganese(II) 2,4-pentanedionate, molybdenum(V)ethoxide, molybdenum(VI) oxide bis(2,4-pentanedionate), neodymium6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionate, neodymiumhexafluoropentanedionate, neodymium(III) 2,4-pentanedionate, nickel(II)2,4-pentanedionate, niobium(V) n-butoxide, niobium(V) n-ethoxide,palladium hexafluoropentanedionate, palladium 2,4-pentanedionate,platinum hexafluoropentanedionate, platinum 2,4-pentanedionate, rhodiumtrifuoropentanedionate, ruthenium(III) 2,4-pentanedionate,tetrabutylammonium hexacholoroplatinate(IV), tetrabromoaurate(III)cetylpyridinium salt.

[0150] As an additive, metal fine particles having a size of severalnanometers to 50 nm or less, which are surface-treated so as to enhancean affinity specifically to one polymer phase, can be employed. JapaneseLaid-open Patent Publication No. 10-251,548 discloses a method ofcoating metal particles with a polymer. Japanese Laid-open PatentPublication No. 11-60,891 discloses a method of coating metal particleswith a polymer. For example, metal particles coated with an Ahomopolymer are segregated on the A polymer chain in an A-B blockcopolymer, whereas metal particles coated with a B homopolymer aresegregated on the B polymer chain in an A-B block copolymer. In thiscase, the metal particles are segregated on a polymer phase exhibiting ahigh affinity in the polymer chains constituting the A-B blockcopolymer. Further, metal particles coated with an A-B block copolymerare segregated at the interface between the A polymer chain and Bpolymer chain. By using such methods, the same type of metal element canbe segregated freely on an arbitrary polymer chain.

[0151] An additive may be chemically bonded to the side chain or mainchain of the block copolymer, instead of merely mixing with the blockcopolymer. In this case, by modifying only a specific polymer with afunctional molecular structure, it becomes easily possible to segregatethe additive on a specific phase. The additive may be introduced into apolymer chain by a method that a structure capable of easily bonding tothe additive is introduced into the main chain or side chain of aspecific polymer, and then a vapor or solution of the additive isbrought into contact with the polymer before or after the formation ofthe phase-separated structure. For example, when chelate structures areintroduced into a polymer chain, the polymer chain can be selectivelydoped with metal ions in a high concentration. The chelate structure maybe introduced into the main chain of a copolymer, or introduced into theester moiety of polyacrylate as a substituent group. When anion-exchange resin structure having an ionic group such as a pyridiniumsalt structure is introduced into a copolymer, the polymer chain can beeffectively doped with a metal ion by counter ion exchange.

[0152] The addition of a plasticizer to the pattern-forming material ispreferable as it enables to form a structure having micro polymer phasesby short time annealing. Although the addition amount of the plasticizeris not particularly restricted, the amount is set to 1 to 70 wt %,preferably 1 to 20 wt %, more preferably 2 to 10 wt % based on a blockcopolymer or a graft copolymer. If the amount of the plasticizer is toosmall, the effect of accelerating the formation of structure havingmicro polymer phases cannot be obtained sufficient, whereas if thecontent of plasticizer is excessive, the regularity of the structurehaving micro polymer phases may be disturbed.

[0153] Examples of the plasticizer include an aromatic ester and fattyacid ester. Specific examples of the ester are a phthalate-basedplasticizer such as dimethyl phthalate, dibuthyl phthalate,di-2-ethylhexyl phthalate, dioctyl phthalate and diisononyl phthalate; atrimellitic acid-based plasticizer such as octyl trimellitate; apyromellitic acid-based plasticizer such as octyl pyromellitate; and aadipic acid-based plasticizer such as dibutoxyethyl adipate,dimethoxyethyl adipate, dibutyldiglycol adipate and dialkyleneglycoladipate.

[0154] A polymerizable low-molecular weight compound can be added as aplasticizer. For example, the polymerizable low-molecular weightcompound such as bismaleimide is added to a block copolymer or graftcopolymer having a polymer chain having a relatively high glasstransition temperature, such as a polyimide chain or a polyamic acidchain that is the precursor of the former. The polymerizablelow-molecular weight compound serves as the plasticizer that enhancesfluidity of the polymer chain and promotes formation of thephase-separated structure in heating process. In addition, since thepolymerizable low-molecular weight compound is finally polymerized andcured to fix the structure having micro polymer phases, which makes itpossible to strengthen the porous structure.

[0155] Examples of bismaleimide include bis(4-maleimidophenyl)methane,bis(4-maleimidophenyl) ether,2,2′-bis[4-(paraminophenoxy)phenyl]propane, and2,2′-bis[4-(paraminophenoxy)phenyl]hexafluoropropane. The additionamount of the bismaleimide is set to 1 to 70 wt %, preferably 1 to 20 wt%, and more preferably 2 to 10 wt %. If the addition amount is toosmall, the cross-linkage density is decreased, whereas if the additionamount is too large, the structure having micro polymer phases is likelyto be disturbed. In the case where reinforcement of the structure havingmicro polymer phases by the polymerized product of the bismaleimide isintended, it is preferable to increase the addition amount of thebismaleimide. Specifically, it is preferable to add the bismaleimide inthe range of 10 to 50 wt % based on a polymer chain to be plasticizedsuch as a polyamic acid chain.

[0156] Addition of a cross-linking agent or introduction of across-linkable group to copolymers enables the copolymers to becross-linked tree-dimensionally with each other after the formation ofthe structure having micro polymer phases. Such a cross-linkage canimprove thermal or mechanical strength of the structure having micropolymer phases more effectively and can enhance stability thereof.Taking heat resistance into consideration, it is preferable therespective polymer chains are essentially incompatible. However, even ifthe structure having micro polymer phases is constituted by phases notincompatible, the heat resistance thereof can be improved bycross-linking the polymer chains forming the phases with each other.

[0157] When a structure having micro polymer phases is formed from ablock copolymer, it is general to anneal the copolymer above the glasstransition temperature (and below the thermal decompositiontemperature). However, if the annealing is performed under anoxygen-containing atmosphere, there is a possibility that the polymer isdegenerated or degraded by an oxidation reaction, which makes itimpossible to form a good structure having micro polymer phases, or thetreatment time is prolonged, or desired etching selectivity cannot beobtained. In order to prevent such degradation of the copolymer, it ispreferable to perform the annealing under an oxygen-free condition andpreferably at a dark place where photo-degradation is hard to occur.However, the annealing under the oxygen-free condition requires strictcontrol of the atmosphere, which is likely to bring about increase inmanufacturing cost. Consequently, it is preferable to add an antioxidantor a light stabilizer to a block copolymer or graft copolymer. Althoughthe antioxidant or light stabilizer is not particularly limited, it ispreferable to employ a radical scavenger capable of trapping radicalspecies generated through an oxidation reaction or photo-degradationreaction.

[0158] Specifically, it is possible to employ a phenol-based antioxidantsuch as 3,5-tert-butyl-4-hydroxytoluene; a phosphorus-based antioxidant;a sulfur-based antioxidant such as a sulfide derivative; a hinderedamine light stabilizer (HALS) represented by a piperidine-based compoundsuch as bis-(2,2,6,6-tetramethylpiperidinyl-4) sebacate; or a metalcomplex-based light stabilizer such as copper and nickel.

[0159] Although the mixing amount of the antioxidant or light stabilizeris not particularly limited, the amount is set to 0.01 to 10 wt %,preferably 0.05 to 1 wt %, and more preferably 0.1 to 0.5 wt %. If themixing amount is too small, antioxidant effect or light stabilizingeffect becomes insufficient. If the mixing amount is excessive, there isa possibility to disturb the phase-separated structure of the copolymer.

[0160] The antioxidant or light stabilizer may disturb smooth thermaldecomposition of a heat decomposable polymer chain on one hand.Therefore, it is preferable to employ those that can be evaporated ordecomposed at a temperature not lower than the heat decompositiontemperature of the heat decomposable polymer chain as the antioxidant orlight stabilizer. In addition, in the case where heat-resistant polymerchain is made infusible by heating in air so as to improve heatresistance, the presence of such an antioxidant should better beavoided. In this case, it is preferable for the antioxidant not to beevaporated at a temperature at which a structure having micro polymerphases is formed but to be evaporated or decomposed at a temperature atwhich the polymer chain is made infusible. Therefore, it is preferableto employ a compound such as 3,5-di-tert-butyl-4-hydroxytoluene that hasa low-molecular weight and is easily evaporated.

[0161] A method for forming a pattern according to the -presentinvention will be described in more detail hereinafter.

[0162] The method for forming a pattern of the present inventioncomprises steps of: forming a film made of a pattern forming material ona substrate; forming a structure having micro polymer phases in thefilm; removing one polymer phase selectively from the structure havingmicro polymer phases formed in the film; and etching the substrate withusing the remaining another polymer phase to transfer the pattern of thestructure having micro polymer phases to the substrate.

[0163] This method can be applied to manufacturing of a fineparticles-dispersed type magnetic recording medium and a field emissiondisplay. Since the positions of elements in the pattern may not berequired so precise in these applications, this method is veryeffective.

[0164] First, a film made of a pattern forming material is formed on asubstrate by spin coating or dip coating. Annealing is performed, ifdesired, at a temperature above the glass transition temperature of thepattern forming material. The thickness of the film is preferably set toa thickness similar to or slightly larger than the size of the domainsin the structure having micro polymer phases to be formed. The size ofthe domain means a diameter of the islands in the case of sea-islandstructure, and a diameter of the cylinders in the case of cylindricalstructure. Specifically, the film thickness is preferably set to 0.5 to2.5 times, and more preferably 0.8 to 1.5 times relative to the domainsize.

[0165] In the case where employed as the pattern forming material is ablock copolymer comprising two polymer chains whose ratio betweenN/(Nc−No) values of respective monomer units is 1.4 or more, where Nrepresents total number of atoms in the monomer unit, Nc represents thenumber of carbon atoms in the monomer unit, No represents the number ofoxygen atoms in the monomer unit, or a block copolymer comprising apolysilane chain and a carbon-based organic polymer chain, the film isdry-etched to remove selectively one phase from the structure havingmicro polymer phases. For example, in a block copolymer comprising apolymer chain containing an aromatic ring and an acrylic polymer chain,the acrylic polymer phase is selectively dry-etched. Further, in a blockcopolymer comprising a polysilane chain and a carbon-based organicpolymer chain, the acrylic polymer phase is selectively dry-etched.

[0166] In the case where employed as the pattern forming material is ablock copolymer comprising a polymer chain whose main chain is cut byirradiation with an energy beam and an indecomposable polymer chainagainst irradiation with an energy beam, the film is irradiated with anenergy beam so as to cut the main chain of one polymer phase, and thenthe polymer phase is evaporated by heating or the polymer phase iswet-etched, thereby removing selectively the polymer phase. For example,when PS-PMMA having micro polymer phases is irradiated with an electronbeam and then developed with a developer, a PMMA phase is selectivelyremoved.

[0167] In the case where employed, as the pattern forming material is ablock copolymer comprising a thermally decomposable polymer chain and aheat resistant polymer chain, heating the film above the thermaldecomposition film enables to evaporate the thermally decomposablepolymer phase constituting the structure having micro polymer phases andto remove selectively the polymer phase.

[0168] These methods make it possible to the film porous. The substrateis dry-etched or wet-etched using the resultant porous film as a mask,thereby transferring the pattern corresponding to the structure havingmicro polymer phases.

[0169] The method using an energy beam has an advantage that it can forma mask by wet etching without using a dry-etching process.

[0170] The thermal decomposition method makes it possible to form a maskby only heat treatment. Further, since the surface of the substrateexposed at the holes of the mask is likely to be etched very easily, itcan provide a high contrast relative to the surface of the substratecovered with the mask. Since not only dry etching but also wet etchingcan be employed for etching of the substrate, the range of selection ofthe substrate material that can be processed is made wide. When the wetetching is employed, process cost can be reduced.

[0171] In a conventional method for forming a mask in which a filmhaving micro polymer phases is made porous by decomposing with ozone, ittakes a long time for decomposition with ozone. The method of thepresent invention can be carried out in shorter time compared to theconventional method. In particular, the thermal decomposition methodmakes it possible to form a good porous pattern in very short time,because it suffices to carry out heat treatment.

[0172] An example of application of the aforementioned pattern formingmethod to manufacturing of the magnetic recording medium will bedescribed. This method comprises the following steps. (a) A nonmagneticsubstrate is coated with a block copolymer comprising two kinds ofpolymer chains whose etching resistivity differs with each other. (b)The block copolymer layer is allowed to form a sea-island structurehaving micro polymer phases. (c) A polymer phase poor in dry-etchingresistivity is dry-etched, and further the nonmagnetic substrate isdry-etched using the remaining dry-etching resistant polymer phase as amask. (d) A magnetic layer is deposited in an etched region of thenonmagnetic substrate. (e) The remaining polymer and the magnetic layerthereon is lifted off. Hereinafter, each of the steps will be describedin more detail.

[0173] (a) As a block copolymer comprising two kinds of polymer chainswhose etching resistivity differs with each other, used is, for example,one comprising dry-etching resistant PS and PMMA that is a polymer poorin dry-etching resistivity in a ratio of about 8:2 or 2:8, where PMMAhaving a molecular weight of 50,000 or less and molecular weightdispersion of 1.1 or less. A solution in which the block copolymer isdissolved in, for example, a cellosolve-based solvent is applied to asubstrate by spin coating or the like.

[0174] (b) Annealing is performed to allow the block copolymer to form astructure having micro polymer phases, thereby forming a sea-islandstructure. An example of the sea-island structure includes a structurein which islands of PMMA having an average size of about 10 nm aredispersed in sea of PS. In the block copolymer, the etching selectivityby reactive ion etching (RIE) using CF₄ becomes to PS:PMMA=1:4 or more,and thus the etch rate of the islands is made larger.

[0175] (c) By performing RIE using CF₄, only the islands or sea of PMMAhaving a higher etch rate in the block copolymer of the sea-islandstructure are etch-removed, and the sea or islands of PS are leftremained. Subsequently, the non-magnetic substrate is etched using theremaining PS phase as a mask, thereby forming holes corresponding toportions of the islands or sea. Note that the (d) step may be preformedwithout etching the nonmagnetic substrate.

[0176] (d) A magnetic material is sputtered such that a magnetic layeris deposited on the etched regions in the nonmagnetic substrate and onthe remaining PS phase. Note that, an underlayer may be deposited priorto deposition of the magnetic layer.

[0177] (e) The remaining PS phase and the magnetic layer thereon arelifted off using a solvent. Further, the remaining organic substance isfinally removed by ashing or the like.

[0178] With using the above steps of (a) to (e), a magnetic layer can beformed in the nonmagnetic substrate or on the nonmagnetic substrate inaccordance with the pattern of the sea-island structure in the blockcopolymer layer. Since the method needs no mask-forming process, it isclearly understood that the method is inexpensive compared to the methodthat forms a mask by electron-beam writing. In addition, since aplurality of media can be annealed simultaneously, the method canmaintain high throughput.

[0179] An example of application of another pattern forming methodaccording to the present invention to manufacturing of the magneticrecording medium will be described with reference to FIGS. 4A to 4C. Themethod uses a block copolymer and a polymer including metal fineparticles as a pattern forming material, which method makes it possibleto arrange the metal fine particles at specific positions on a substratewithout a lift-off process.

[0180] First, a solution of a blend of an A-B block copolymer and an Ahomopolymer including metal fine particles is prepared, and the solutionis applied to the substrate 1 to form a film. As the A-B blockcopolymer, one having an acrylic polymer chain and aromatic-basedpolymer chain is employed, for example. In addition, as a polymercovering the metal fine particles, a polymer other than the A polymercan be employed as long as the polymer has a similar molecular structureto the A polymer and is incompatible with the B polymer. Annealing thefilm at a temperature above the glass transition temperature forms astructure having micro polymer phases in which the islands of the Apolymer phase 4 are present in the sea of the B polymer phase 3. In thisprocess, the metal fine particles covered with the A homopolymer aresegregated on the A polymer chain 4 constituting the structure havingmicro polymer phases, and thus the metal fine particles 5 are positionedat the central portions of the A polymer phases 4. In such a manner, astructure in which the metal particles are positioned at the centralportions in the island-like polymer phases can be formed with onlyperforming annealing of the film of pattern forming material (FIG. 4A).Incidentally, when metal fine particles covered with an A-B blockcopolymer instead of the A homopolymer are used, the metal fineparticles are segregated at the interface between the A polymer phaseand B polymer phase.

[0181] Then, with performing RIE, only the A polymer phases 4 (here, theacrylic polymer phases) constituting the structure having micro polymerphases are selectively etched. In this case, the metal fine particles 5are left remained in the holes 6 being formed without being etched (FIG.4B).

[0182] Further, when etching is continued using the remaining B polymerphase 3 as a mask, the holes 7 are formed in the substrate 1, and themetal fine particles 5 are left remained at the bottom of the holes 7 inthe substrate 1. Thereafter, the remaining B polymer phase 3 issubjected to ashing with oxygen plasma (FIG. 4C). By depositing magneticmaterial using the metal fine particles 5 present at the bottom of theholes 7 as seeds, a magnetic recording medium is formed.

[0183] The above method makes it possible to arrange the metal fineparticles at specific positions in the substrate without a lift-offprocess. Depositing a conductor or semiconductor on the metal fineparticles makes it also possible to apply the method for forming anemitter of a field emission display.

[0184] Incidentally, it is preferable to select a pattern formingmaterial to be used appropriately. In order to form holes by etching agate electrode of a field emission array, in which holes emitterelectrodes are formed, it is preferable to use such a pattern formingmaterial as follows. For example, the pattern forming material consistsof a block copolymer or graft copolymer comprising an aromaticring-containing polymer chain and an acrylic polymer chain having amolecular weight of 50,000 or more and molecular weight distribution(Mw/Mn) of 1.15 or less in which the molecular weight ratio between thearomatic ring-containing polymer chain and acrylic polymer chain rangesfrom 75:25 to 90:10.

[0185] In order to manufacture a magnetic recording medium of fineparticle-dispersed structure, it is preferable to use such a patternforming material as follows. For example, the pattern forming materialconsists of a block copolymer or graft copolymer comprising an aromaticring-containing polymer chain and an acrylic polymer chain having amolecular weight of the acrylic polymer chain of 100,000 or less andmolecular weight distribution (Mw/Mn) of 1.20 or less in which themolecular weight ratio between the aromatic ring-containing polymerchain and acrylic polymer chain ranges from 75:25 to 90:10.

[0186] In either pattern forming material, a minority phase (here, theacrylic polymer phase) is removed by dry etching or by irradiation withan energy beam. The size of the pattern in the structure having micropolymer phases is uniquely determined by the molecular weight of theminority polymer phase to be removed. Therefore, it is preferable to setthe molecular weight of the minority polymer to 100,000 or less. Whenthe polymer meets the condition, a dot pattern of a diameter rangingfrom 100 to 200 nm can be provided independently of the polymer type. Inthe case where a dot pattern of about 40 nm is to be formed, it ispreferable to set the molecular weight of the minority polymer to about10,000. If the molecular weight of the minority polymer becomes lowerthan 3,000, however, sufficient repulsive force between segments, whichis necessary for microphase-separation, cannot be provided, and thusthere is a possibility of disturbing distinct pattern formation.

[0187] A phase-separated structure of a pattern forming film can beoriented by an electric field. When an electric field of 1 to 10 V/μm isapplied during formation of the structure having micro polymer phases inthe pattern forming film by annealing, the structure having micropolymer phases is oriented. In the case of a cylindrical structure, forexample, the cylinder phases are oriented along electric flux lines.When a voltage is applied to the pattern forming film along thedirection parallel to the substrate, the cylinder phases are orientedalong the direction parallel to the substrate. Etching the substrateusing the oriented pattern forming film as a mask makes it possible toform a linear pattern in the substrate. On the other hand, when avoltage is applied to the pattern forming film with providing parallelplate electrodes above and below the pattern forming film, the cylinderphases are oriented along the thickness direction. With heat-treatingthe pattern forming film to make porous, a porous film having a highaspect ratio in the depth direction. Etching the substrate using theoriented pattern forming film as a mask makes it possible to form holeshaving a very high aspect ratio in the substrate.

[0188] According to the present invention, it is also possible byutilizing a pattern transfer technique to transfer a structure havingmicro polymer phases pattern of a pattern forming material to a patterntransfer film and further to a substrate, thereby enabling to form holeshaving a high aspect ratio in the substrate. Note that, a lower patterntransfer film may be provided between the substrate and the patterntransfer film. The pattern forming film, the pattern transfer film andthe lower pattern transfer film will be described below.

[0189] 1. Pattern Forming Film

[0190] As for a pattern-forming film, a block copolymer comprising twokinds of polymer chains whose dry etch rate ratio is 1.3 or more; ablock copolymer having a polymer chain whose main chain is cut byirradiation with an energy beam and an indecomposable polymer chainagainst irradiation with an energy beam; or a block copolymer having athermally decomposable polymer chain and a heat resistant polymer chain,which contains one transformed form a precursor, can be employed. Such ablock copolymer is applied by spin coating or dip coating to form apattern forming film. In this case, a pattern forming film in whichcylinder phases are oriented by orientation with an electric field.

[0191] 2. Pattern Transfer Films

[0192] The pattern transfer film is a layer to which a pattern formed inthe pattern forming film is to be transferred, the film being providedunder the pattern forming film. After one polymer phase constituting thepattern forming film is selectively removed, the pattern transfer filmis subsequently etched. In order to remove one polymer phase in thepattern forming film, dry etching, electron-beam irradiation and wetetching, or thermal decomposition is employed in accordance with theabove pattern forming material.

[0193] The thickness and etch rate of the pattern transfer film is setso that the etching of the pattern transfer film can be accomplishedbefore a phase having a higher etch resistance in the copolymer of thepattern forming film is etched. Specifically, it is preferable that thepattern transfer film has a dry etch rate ratio of 0.1 or more, morepreferably 1 or more, still more preferably 2 or more compared to thepolymer chain exhibiting lowest dry etch rate among the polymer chainsconstituting the block copolymer constituting the pattern-forming film.As for the pattern transfer film, a metal thin film formed of Au, Al,Cr, etc.; polysilane; or a polymer having N/(Nc−NO) value of 3 or morethat is easily etched.

[0194] The polysilane as a pattern transfer film is not particularlyrestricted as long as it contains a repeating unit represented by thefollowing chemical formulas.

[0195] where R¹ and R² represent a substituted or unsubstituted alkyl,aryl or aralkyl group having 1 to 20 carbon atoms, respectively.

[0196] Examples of the polysilane include poly(methylphenylsilane),poly(diphenylsilane) and poly(methylchloromethylphenylsilane). Further,the polysilane may be a homopolymer or a copolymer, or may be one havinga structure that two or more kinds of polysilane are bonded with eachother via an oxygen atom, a nitrogen atom, an aliphatic group or anaromatic group. An organosilicon polymer in which a polysilane and acarbon-based polymer are copolymerized can also be employed. Althoughthe molecular weight of the polysilane is not particular restricted, apreferable range of the molecular weight is Mw=2,000 to 1,000,000, morepreferably Mw=3,000 to 100,000. If the molecular weight is too small,the coating property and etch resistance of the polysilane will bedeteriorated. In addition, if the molecular weight is too small, thepolysilane film is dissolved when the pattern forming film is applied,thereby giving rise to mixing between the both films. On the other hand,if the molecular weight is too large, solubility of the polysilane to acoating solvent will be deteriorated.

[0197] Incidentally, since polysilane is liable to be oxidized and itsetching property is liable to be changed, it is preferable to add theaforementioned antioxidant or light stabilizer. Although the additionamount of the additives is not particularly restricted, it is preferableto be 0.01 to 10 wt %, more preferably 0.05 to 2 wt %. If the additionamount is too small, effect by addition cannot be obtained, on the otherhand, if the addition amount is too excessive, there is a possibilitythat the etching property of polysilane is deteriorated.

[0198] 3. Lower Pattern Transfer Film

[0199] Provision of the lower pattern transfer film, although the lowerpattern transfer film may not necessarily be provided, enables to obtaina pattern having a high aspect ratio as well as to widen selectionranges of substrate materials to be processed. Since the lower patterntransfer film is etched using the pattern transfer film as a mask, towhich the structure having micro polymer phases has been transferred,the etching selectivity of the lower pattern transfer film relative tothe pattern transfer film is preferably set to 2 or more, morepreferably 5 or more, still more preferably 10 or more. In order to givehigh etching selectivity, it is preferable to use an inorganic thin filmmade of metal or metal oxide as a pattern transfer film for a patterforming film made of an organic polymer, and to use an organic polymerfilm as a lower pattern transfer film. In this case, etching the lowerpattern transfer film with O₂ gas using the pattern transfer film as amask enables to form very deep holes. Etching the substrate using thesefilms as masks makes it possible to form deep holes having a high aspectratio in the substrate. In order to give a high aspect ratio in thedepth direction, it is preferable to etch the lower pattern transferfilm by anisotropy etching. Incidentally, when etching selectivitybetween the pattern transfer film and lower pattern transfer film issufficiently high, the pattern transfer film may be made thin, and thusthe pattern transfer film may be etched by isotropy etching such as wetetching.

[0200] In the case where the lower pattern transfer film is used, it ispreferable to use, as the pattern transfer film, a metal such as Al, AuAg and Pt or a metal oxide such as silica, titanium oxide and tungstenoxide. In particular, aluminum is preferred because it has a gooddeposition property and can be etched by both etching processes of wetetching and dry etching. Although an organic polymer used for the lowerpattern transfer film is not particularly restricted, preferred is apolymer having high dry etch resistance against a freon type gas such asCF₄, for example, polystyrene or a derivative thereof such aspolyhydroxystyrene, polyvinylnaphthalene or a derivative thereof, andnovolak resin. The lower pattern transfer film may not necessarily beformed of a block polymer as well as may not necessarily be uniform inmolecular weight, so that it is possible to use an organic polymer thatcan be mass-produced industrially by means of radical polymerization orthe like and is relatively inexpensive.

[0201] A method for forming a pattern in which lower and upper patterntransfer films and a pattern forming film are formed on a substrate andetching processes are performed thrice will be described.

[0202] First, a film made of a polymer as described above is formed as alower pattern transfer film on a substrate by means of spin coating ordipping. The thickness of the lower pattern transfer film shoulddesirably be equal to or larger than the depth of holes to betransferred. A film formed of an inorganic material such as a metal orSiO is formed as an upper pattern transfer film on the lower patterntransfer film by means of vacuum evaporation or plating. The thicknessof the upper pattern transfer film should desirably be less than thethickness of a pattern forming film to be formed thereon. Any patternforming film as described above is formed on the upper pattern transferfilm. The thickness of the pattern forming film should desirably bealmost the same as the size of a structure to be formed. For example, inthe case where a sea-island structure comprising islands having a sizeof about 10 nm is to be obtained, the thickness of the film shouldpreferably be about 10 nm.

[0203] The dry etch rate of the upper pattern transfer film shouldpreferably be higher than that of the pattern forming film that is madeporous. Specifically, it is preferably that the upper pattern transferfilm is etched in a rate of at least 1.3 times, more preferably twice ormore the rate for the pattern forming film. However, in the case where apolymer film is provided as a lower pattern transfer film under theupper pattern transfer film, the above etch rate ratio may notnecessarily be met. Namely, after the upper pattern transfer film isetched, the lower pattern transfer film is etched with oxygen plasma. Onthis occasion, when the upper pattern transfer film has high resistanceagainst oxygen plasma, the lower pattern transfer film can be easilyetched with oxygen plasma. In this case, the dry etch rate of the upperpattern transfer film may be 0.1 or so compared to that of the patternforming film.

[0204] After these films are formed as mentioned above, annealing isperformed, if desired, thus a structure having micro polymer phases isformed in the pattern-forming film. RIE with a fluorine-based gas,electron-beam irradiation and wet etching, or thermal decomposition isperformed, thereby removing one polymer phase selectively in thestructure having micro polymer phases formed in the film and leavinganother polymer phase. The upper pattern transfer film (for example, ametal) is etched to transfer the structure having micro polymer phases(for example, a sea-island structure) to the film. Then, RIE with oxygenplasma is performed using the remaining upper pattern transfer film as amask, thereby etching the lower pattern transfer film (for example, apolymer). Since oxygen RIE does not etch the upper pattern transfer filmformed of a metal, but etches only the lower pattern transfer filmformed of an organic polymer, it is possible to form a structure havinga very high aspect ratio. Simultaneously, the pattern forming filmformed of an organic copolymer is subjected to ashing. RIE with afluorine-based gas is performed again using the remaining lower patterntransfer film as a mask, thereby etching the substrate. As a result,holes of the order of nanometers and having a very high aspect ratio canbe formed in the substrate. Although wet etching can be employed inplace of RIE in the above processes, the shape of the pattern is likelyto be deformed during the pattern transfer process.

[0205] A method for manufacturing various porous structures using apattern forming material of the present invention will be described.

[0206] A method for manufacturing a porous structure of the presentinvention comprises the steps of: forming a molded product made of apattern forming material comprising a block copolymer or graftcopolymer; forming a structure having micro polymer phases in the moldedproduct; and dry-etching the molded product to remove selectively apolymer phase from the structure having micro polymer phases, therebyforming a porous structure.

[0207] The structure having micro polymer phases formed in the bulkmolded product of a block copolymer or graft copolymer is preferred tobe a continuous phase structure such as a cylindrical structure, alamella structure and a bicontinuous structure, and particularlypreferred is the bicontinuous structure. The bicontinuous structureincludes morphology such as an OBDD structure, a Gyroid structure, aT-surface structure and a lamella catenoid structure.

[0208] In the case where used as the pattern forming material is a blockcopolymer comprising two polymer chains whose ratio between N/(Nc−No)values of respective monomer units is 1.4 or more (where N representstotal number of atoms in the monomer unit, Nc represents the number ofcarbon atoms in the monomer unit, No represents the number of oxygenatoms in the monomer unit), or a block copolymer comprising a polysilanechain and a carbon-based organic polymer chain, the film is dry-etchedto remove selectively one polymer phase from the structure having micropolymer phases.

[0209] In the case where used as the pattern forming material is a blockcopolymer comprising a polymer chain whose main chain is cut byirradiation with an energy beam and an indecomposable polymer chainagainst irradiation with an energy beam, the film is irradiated with anelectron beam to cut the main chain of one polymer phase constitutingthe structure having micro polymer phases, followed by wet-etching,thereby removing the polymer phase selectively.

[0210] In the case where used as the pattern forming material is a blockcopolymer comprising a thermally decomposable polymer chain and a heatresistant polymer chain, which contains one transformed form aprecursor, the film is heated to a temperature above the thermaldecomposition temperature to evaporate the thermally decomposablepolymer phase constituting the structure having micro polymer phases,thereby removing the polymer phase selectively.

[0211] Among these methods, the method of performing energy beamirradiation and wet etching and the thermal decomposition method arepreferred because the steps are made simple, the cost is lowered, and arelatively thick porous structure can be manufactured.

[0212] For example, used is a block copolymer having an indecomposablepolymer chain constitutes the porous structure and a polymer chain to beremoved by energy beam irradiation and wet etching. As for the energybeam to be irradiated, an electron beam (β ray), X-ray and γ-ray arepreferable because they have higher penetration property into a moldedproduct. In particular, the electron beam is most preferred because ithas high selectivity in decomposition reaction, has high decompositionefficiency and can be applied at a low cost.

[0213] Examples of the indecomposable polymer chain constituting theporous structure include polystyrene; polystyrene derivatives such aspolyhydrostyrene; novolak resin; polyimide; acrylonitrile-based resinsuch as acrylonitrile homopolymer and a copolymer of acrylonitrile andanother vinyl polymer; polyacrylic acid, and polyacrylate such aspolymethyl acrylate and polytrifluoroethyl-α-chloroacrylate; vinylidenefluoride-based resin such as vinylidene fluoride homopolymer and acopolymer of vinylidene fluoride and hexafluoropropylene; vinylchloride-based resin; vinylidene chloride-based resin; aromatic ketoneresin such as polyether ketone and polyether ether ketone; polysulfone;and polyether sulfone. In particular, acrylonitrile-based resin andvinylidene fluoride-based resin are preferred in view of durability.

[0214] Examples of a polymer chain that is cut in the main chain andremoved by energy beam irradiation include polyolefin such aspolypropylene and polyisobutylene; poly-α-methylstyrene; polymethacrylicacid and polymethacrylate such as polymethyl methacrylate andpolytrichloroethylmethacrylate; polymethacrylamide; polyolefin sulfonesuch as polybutene-1-sulfone, polystyrenesulfone,poly-2-butylenesulfone; and polymethyl isopropenyl ketone. Inparticular, preferred are polyhexafluorobutyl methacrylate andpolytetrafluoropropyl methacrylate that are polymethacrylate in whichfluorine is introduced, and polytrifluoroethyl-α-chloroacrylate that ispolymethacrylate in which the α-methyl group is substituted by chlorine.

[0215] In the case where the method of applying electron-beam isemployed, it is particularly preferable to use, as a polymer chainconstitutes the porous structure, a polymer having double bonds such as1,2-polybutadiene in which cross-linking reaction can be advanced byelectron beam irradiation, derivatives of polynorbornen orpolycyclohexane, and vinylidene fluoride-based resins such as acopolymer of vinylidene fluoride and hexafluoropropylene.

[0216] As the block copolymer having a thermally decomposable polymerchain and a heat resistant polymer chain, various block copolymers thathave been already described can be employed. Further, after the porousstructure made of a polymer is formed, the structure is fired andcarbonized, and thus a porous carbon structure can also be manufactured.

[0217] The manufactured porous structure can be applied to various uses.Specific uses include a separator of an electrochemical cell, a filtersuch as a hollow fiber filter, ultra-fine fiber and porous fiber.

[0218] In another method of manufacturing a porous structure of thepresent invention, a porous structure is formed from a molded product ofa pattern forming material containing a block copolymer by such methodsas described above, and then the pores in the porous structure arefilled with an inorganic substance. This is a method for manufacturing astructure of the inorganic substance using the pores, which are formedby transferring the structure having micro polymer phases of the blockcopolymer or graft copolymer, as a template.

[0219] For example, a molded product is formed by casting or meltingwith using a pattern forming material containing a block copolymercomprising a thermally decomposable polymer chain and a heat resistantpolymer chain. Next, annealing is performed, if desired, thus astructure having micro polymer phases is formed. Then, the structure isheated to a temperature above the thermal decomposition temperature ofthe thermally decomposable polymer chain to remove selectively thethermally decomposable polymer chain, thereby forming a porous structureretaining the structure having micro polymer phases. The pores of theporous structure are filled with, for example, a metal, an inorganiccompound such as a metal oxide and a carbon material such as diamond byplating or CVD. Thereafter, the heat resistant polymer phase isselectively removed by O₂ ashing, if desired, and thus a structure ofinorganic substance is formed. Further, transfer processes may berepeated using the resultant structure of inorganic substance as atemplate to form another structure of organic substance or inorganicsubstance. A porous structure consisting of a heat resistant polymerphase is particularly excellent because it is hard to be thermallydeformed, and besides, it can be easily removed by O₂ ashing or thelike.

[0220] In this method, the pores of the porous structure are filled withan inorganic substance by plating or CVD. Therefore, it is preferablethat openings are present on the surface of the porous structure andcontinuous pores are present in the porous structure. As a structurehaving micro polymer phases capable of forming pores as above, acylindrical structure, a bicontinuous structure or a lamella structureis preferred. In particular, the cylindrical structure and bicontinuousstructure are excellent because they can easily retain the shape of thepores in the porous structure. The OBDD structure and Gyroid structureincluded in the bicontinuous structure are particularly preferredbecause they are easily filled with a metal.

[0221] In the case where the porous structure is a thin film having athickness nearly equal to the domain size of the structure having micropolymer phases, a sea-island structure may be formed. When the porousstructure of the sea-island structure is used as a template, a dotpattern of an inorganic substance can be formed. For example, a porousfilm exhibiting a sea-island structure is formed on a conductivesubstrate consisting of, for example, a metal. At that time, theconductive substrate is exposed to outside at the bottom of holes. Whenthe substrate is not exposed to outside, the substrate is made exposedto outside by lightly etching the porous film with oxygen plasma.Plating by passing an electric current through the conductive substratecan form a dot-like metal pattern.

[0222] Alternatively, a porous film exhibiting a sea-island structure isformed on a hydrophilic glass substrate to make the glass substrateexposed to outside at the bottom of the holes. Then, electroless platingis performed by adding a catalyst to deposit a metal on the bottom ofholes, thereby making it possible to a dot-like metal pattern.

[0223] In order to fill the porous structure with a metal, an inorganiccompound or carbon, used is a liquid phase process such as plating or avapor phase process such as CVD.

[0224] In the case of metal filling, electroplating or electrolessplating is employed. The electroplating is performed with connecting anelectrode to the porous structure. For example, a pattern forming filmis formed on an electrode, and the film is made porous. The electrode isimmersed in a plating bath, and then a current is passed through theelectrode, thereby depositing a metal in the porous structure. In thiscase, it is preferable to perform treatment to make the inner surfacefacing to the holes hydrophilic by plasma treatment, for example, sothat the plating solution can easily penetrate inside the holes in theporous structure.

[0225] After the porous structure is filled with a precursor of metal ormetal oxide such as an organic metal compound, the porous structure maybe fired so as to be evaporated as well as the precursor may beconverted into a metal or metal oxide. As the precursor of metal, anorganic metal salt, silsesquioxane, etc., can be employed. As a methodfor filling with these precursors, electrodeposition, spin coating,evaporation, sputtering, impregnation, etc., can be employed.

[0226] Also in the case of manufacturing a porous structure, aphase-separated structure of a molded product made of a pattern formingmaterial may be oriented by an electric field in the same manner asdescribed in relation to the method for forming a planar pattern. Forexample, when a film of a pattern forming material is formed on asubstrate and then a voltage is applied to the film in the directionparallel to the substrate, cylinder phases are oriented in the directionparallel to the substrate. Thereafter, when the cylinder phases areremoved by, for example, dry etching or thermal decomposition, thesurface of the substrate is made exposed. Deposition of a metal on theexposed portions of the surface of the substrate by plating or CVD canform striped metal pattern, which can be used as fine metal wires.

[0227] For example, on an insulating wafer made of, for example, siliconnitride, two electrodes are formed with leaving a space of about 5 μm.The wafer is spin-coated with a PGMEA solution of PS-PMMA diblockcopolymer to form a thin film having a thickness of about 10 nm to 1 μm.Annealing is performed at 230° C. for 40 hours with applying a voltageof 10 V between the two electrodes. During the operation, microphaseseparation of the diblock copolymer is caused, and a cylindricalstructure, which is perpendicularly oriented to the electrodes, isformed. The PMMA phases in the structure having micro polymer phases areremoved by reactive ion etching or energy beam irradiation. As a result,a pattern of the order of nanometers perpendicular to the electrodes isformed. When the pattern as a template is filled with a metal byelectroplating or sputtering, ultrafine metal wires can be formed.

[0228] When parallel plate electrodes are provided above and below apattern forming film to apply a voltage, cylinder phases are oriented tothe thickness direction. Removal of the cylinder phases can form aporous film in which narrow holes having a high aspect ratio areoriented in the thickness direction. When one electrode is removed andthe film is immersed in a plating solution to perform electroplating bypassing a current through the remaining electrode, a pinholder-likestructure, in which fine metal wires having a diameter of 10 to 100 nmare oriented in the direction perpendicular to the electrode, can beformed. It is also possible to use such a method that a metal such aspalladium use as a plating nucleus is deposited on a substrate, a porousfilm is formed on the metal using a similar procedure as above, and thenholes are filled with a metal by electroless plating. In this case, whenthe porous film is made appropriately swelled using a solvent, it ispossible to decrease the diameter of holes. When the porous film havingnarrowed holes is used as a template, a pin holder-like structure, inwhich very fine metal wires having a diameter of several nanometers areoriented in the direction perpendicular to the electrode, can be formed.Fine wires of a metal oxide and various ceramic materials or the likecan be formed in a similar method. This structure can be suitablyemployed as emitters in a field emission display (FED). In theapplication to the emitter, it is preferable to form the metal wiresusing gold, chromium, iridium or the like, in that iridium isparticularly preferable in view of heat resistance. In the case offorming emitters in FED, it is preferable that the thickness of theporous film is larger than the length of the metal wires to be formed;specifically, the thickness is preferred to be 1.5 times or more, morepreferably 2 times or more the average length of the metal wires. Thisis because if a metal is deposited not only in the holes but also on thesurface of the porous film, it is difficult to form emitters of a pinholder-like structure. The aspect ratio of the emitters (length/diameterof the metal wires) should preferably be not less than 10, morepreferably not less than 50 to provide excellent field emissioncharacteristics. For example, when emitters having a diameter of 3 nmand an aspect ratio of 10 or more are to be formed, the porous film ispreferred to have a thickness of 45 nm or more.

[0229] In the application to the emitters in FED, the porous film shouldpreferably be removed by ashing or the like because remaining porousfilm becomes a cause of gas generation. However, when a polymer chainconstituting a porous film is made of a material such aspolysilsesquioxane that can be converted into an inorganic material, itis preferable to leave the porous film because the film can retain thepin holder-like structure.

[0230] It is also possible to use a method that metal wires manufacturedas described above are once removed from the electrode and then they areadhered as emitters to another electrode, which is separately prepared.In this case, since emitters can be formed with only using an adhesionstep, the manufacturing process can be simplified. However, since themetal wires are not oriented in many cases, field emission efficiencytends to be lowered.

[0231] When employed is a block copolymer having a polymer chain whosemain chain is cut by irradiation with an energy beam and anindecomposable polymer chain against irradiation with an energy beam,various combinations of polymer chains as described above may beapplied. However, from the viewpoint of orientation characteristics andetching contrast, preferred is a diblock copolymer having a decomposablepolymer chain selected from poly(meth)acrylate such as polymethylmethacrylate, polymethyl acrylate, polytrifluoromethyl-α-chloroacrylateand polytrichloroethyl methacrylate and a indecomposable polymer chainselected from polystyrene, polyhydroxystyrene, polyvinylnaphthalene andderivatives thereof.

[0232] To form a highly oriented cylindrical structure, it is desirableto set the molecular weight ratio between the decomposable polymer andthe indecomposable polymer to the ranges of 75:25 to 67:34 and 34:67 to25:75. In the range of between 67:34 and 34:67, cylinders may possiblycoalesce with each other. If the composition is more weighted comparedto 75:25 or 25:75, it is difficult to give continuous cylindricalstructure.

[0233] Intervals in the pattern can be set to the range of about 10 nmto about 1 μm, depending on the molecular weight of the block copolymer.A block copolymer having a molecular weight of about 10,000 is employedwhere a pattern of a size of about 10 nm is to be formed, and a blockcopolymer having a molecular weight of about 100,000 for a pattern of asize of about 100 nm. If the molecular weight is lower than 3,000, astructure having micro polymer phases is hard to be formed, whereas, ifthe molecular weight exceeds 1,000,000, there is a possibility thatregularity of a structure having micro polymer phases is impaired.

[0234] Next, application of the porous structure of the presentinvention to an electrochemical cell such as a lithium ion secondarybattery or an electrochromic device will be described. FIG. 5 shows aconceptual diagram of an electrochemical cell. The electrochemical cellhas a structure in which provided are the positive electrode 71 and thenegative electrode 72, each of which is provided with a collector, andthe separator 73 impregnated with an electrolyte and interposed betweenthe electrodes.

[0235] In the electrochemical cell of the present invention, used as theseparator 73, for example, is a porous structure formed by removing onepolymer phase selectively from a block copolymer having a structurehaving micro polymer phases. The separator can be manufactured by usinga pattern forming material comprising a block copolymer having, forexample, a polymer chain decomposable by irradiation with an energy beamand an indecomposable polymer chain, as described below. First, a sheetof a pattern forming material is formed, followed by allowing the sheetto form a structure having micro polymer phases. The sheet is irradiatedwith an energy beam to decompose the main chain of one polymer phase.Next, the sheet is placed between the negative electrode and thepositive electrode via a roll-to-roll process, and then they arehot-pressed. The laminate of pressed electrodes and separator is rinsedwith a solvent to remove the polymer phase whose main chain has beendecomposed, thereby making the separator sheet porous. Here, the polymerphase whose main chain has been decomposed may be evaporated and removedby reducing pressure or heating. After being sufficiently dried, thelaminate is immersed in a bath of an electrolytic solution containing asupporting electrolyte, etc., thereby allowing the laminate to beimpregnated with the electrolytic solution. Lead wires, etc., areconnected to the resultant laminate, followed by sealing the laminatewith an aluminum laminate film, for example, thus manufacturing anelectrochemical cell.

[0236] When an accelerating voltage for electron beam is sufficientlyraised, the separator sheet is irradiated with an electron beam passedthrough a collector formed of a metal mesh and an active material forelectrode. Therefore, the polymer main chain can also be decomposed byirradiation with an electron beam after the separator and electrodes arepressed. This method is preferable because the possibility that thephase-separated structure by pressing is minimized.

[0237] It is preferable to mix a spacer consisting of metal oxideparticles (such as silica particles) with the pattern formingcomposition so as to secure a clearance between electrodes when twoelectrodes and a separator are pressed. The size of the metal oxideparticles should preferably be set to about 20 to 90% relative to theclearance between the electrodes.

[0238] In order to make it easy for a washing solution and electrolytesolution to pass through the electrodes to the separator, the positiveelectrode 71 and the negative electrode 72 should preferably be formedinto an intricate structure such as aggregated particles or a porousstructure as shown in FIG. 6. In this case, the separator 73 formed of aporous structure is in a state of intruding in pores of theseelectrodes. The electrodes of intricate structure can be manufactured bya method that an active material for electrode is mixed with a bindercomprising a pattern forming material, followed by being applied to thecollector. Employment of such electrodes makes it possible to preventcontact resistance with an electrolyte from being increased, and at thesame time, to prevent liquid leakage.

[0239] The porous structure constituting the separator should preferablyhave an aggregated structure of domains having a radius of gyration of50 μm or less in which unit cells having radius of gyration of 10 to 500nm are periodically arranged. Such a separator has a good property ofretaining electrolyte solution and is hard to bring about liquid leakagebecause of pores having a size of the order of nanometers as well as isexcellent in ion conductivity because of less structural traps (such asdead-end pores). Particularly preferred is a porous structure havingcontinuous pores to which a bicontinuous phase-separated structure istransferred. Among bicontinuous structures, an OBDD structure and Gyroidstructure are particularly preferred because they exhibit high ionconductivity, which is attributed to the fact that ions are hard to betrapped in these structures, and are also excellent in film strength.The pore size is preferably set to 5 to 200 nm, more preferably 10 to100 nm, although it is not particularly limited. If the pore size is toosmall, ion conduction will be inhibited. If the pore size is too largeon the contrary, retention capacity for electrolyte solution will belowered.

[0240] The electrolyte solution to be impregnated into the separator maybe one that an inorganic salt or organic salt is dissolved in water or apolar solvent, or may be a room-temperature molten-salt. In the case ofa lithium ion secondary battery, an electrolyte solution that a lithiumsalt is dissolved in a polar solvent or in room-temperature molten-saltis employed. As the lithium salt, employed is LiPF₆, LiBF₄, LiClO₄,LiSCN, Li₂B₁₀Cl₁₀, LiCF₃CO₂, lithium triflate, or the like. As the polarsolvent, employed is a carbonate-based solvent such as ethylenecarbonate, propylene carbonate and diethyl carbonate; a lactone-basedsolvent such as γ-butyrolactone; sulfolane-based solvent such assulfolane and 3-methylsufolane; and ether-based solvent such as1,2-dimethoxyethane and methyldiglyme. As the room temperaturemolten-salt, employed is an imidazolium salt such as1-methyl-3-ethylimidazolium triflate and a pyridinium salt such asN-butylpyridinium triflate.

[0241] As the negative electrode, employed is a copper mesh coated witha mixture comprising an active material for negative electrode such asgraphite and hard carbon, conductive graphite and a binder polymer,preferably a pattern forming material. As the positive electrode,employed is an aluminum mesh coated with a mixture comprising an activematerial for positive electrode such as lithium cobaltate, conductivegraphite and a binder polymer, preferably a pattern forming material.

[0242] In an electrochemical cell of the present invention, electrodesmay consist of a porous structure formed by selectively removing apolymer phase from a block copolymer having a structure having micropolymer phases.

[0243] Such a porous structure can be formed by, for example, a methodthat a structure having micro polymer phases is formed in a moldedproduct consisting of a block copolymer having a thermally decomposablepolymer chain and a heat-resistant polymer chain and then the thermallydecomposable polymer is decomposed and evaporated to form pores, therebymaking the molded product porous. As the method for making the moldedproduct porous, it is possible to employ a method of decomposing andremoving a specific polymer phase by irradiation with an electron beamand a method of removing a specific polymer phase by dry etching.

[0244] It is particularly preferable to form a porous carbon electrodeusing a carbon precursor polymer as a heat-resistant polymer phase andfiring the heat-resistant polymer phase made porous. Examples of carbonprecursor polymer include polyacrylonitrile, polymethacrylonitrile,polyimide derivatives, polyaniline derivatives, polypyrrole derivatives,polythiophene derivatives, polyparaphenylenevinylene derivatives, andpolycyclohexadiene derivatives.

[0245] Annealing a molded product of a block copolymer having a carbonprecursor polymer and a thermally decomposable polymer is performed toform a structure having micro polymer phases. The thermally decomposablepolymer is decomposed to remove by heating, thereby forming a porousstructure consisting of the remaining carbon precursor polymer. Firingthe porous structure makes it possible to provide a porous carbonelectrode to which the structure having micro polymer phases istransferred. When the structure having micro polymer phases is acylindrical structure, lamella structure or bicontinuous structure, aporous carbon electrode containing continuous pores is given. Such aporous carbon electrode can be suitably used for a carbon negativeelectrode for a lithium ion secondary battery, an electrode for a fuelcell, an electrode for an electric double layer capacitor, etc. Inparticular, a porous carbon electrode that retains a bicontinuousstructure is excellent in interfacial area and morphology retention.Among bicontinuous structures, preferred is an OBDD structure or Gyroidstructure.

[0246] A porous structure, to which a structure having micro polymerphases is transferred, can be formed using a blend of a block copolymerand a carbon precursor, the block copolymer comprising a thermallydecomposable polymer chain and a polymer chain having high affinity withthe carbon precursor. It is preferable to applying an energy beam suchas an electron beam to cross-link the carbon precursor polymer chains.In this case, the structure having micro polymer phases is hard to becollapsed when the porous structure is fired. Alternatively, the carbonprecursor polymer chains may be oxidatively cross-linked by heattreatment in air.

[0247] The firing temperature is set to 500 to 1500° C. for the negativeelectrode for use in a lithium ion secondary battery, and to 800 to3000° C. for the electrode for use in a fuel cell or the electrode foruse in a electric double layer capacitor. In order to improveconductivity of the porous carbon, it is preferable to perform firingfrom 2000 to 3000° C. to advance graphitization.

[0248] A porous carbon electrode can be manufactured from a blockcopolymer consisting of a carbon precursor polymer chain and a polymerchain capable of forming a SiO analogue. The polymer chain capable offorming the SiO analogue includes polysilanes having a Si—H group oralkoxyl group in the side chains; polysiloxanes such as a polysiloxanehaving an alkoxyl group in the side chains such as polydialkoxysiloxane;silsesquioxanes; a polymer chain having a siloxane cluster such as POSS(Polyhedral Oligomeric Silsesquioxane: polysiloxane T₈-cube).

[0249] When such a porous carbon forming material is fired, formed is ananocomposite consisting of a carbon phase, in which a structure havingmicro polymer phases is retained, and a phase of a SiO analoguematerial. When the nanocomposite is subjected to acid or alkalitreatment so that the SiO phase is selectively decomposed and removed, aporous carbon used for a carbon electrode can be provided. This formingmethod can prevent the nanopores from being collapsed through thermaldeformation during firing.

[0250] The carbon electrode formed in such a manner and having regularlyarranged nanopores can be used well for the carbon electrode for anelectrochemical cell such as a lithium ion secondary battery, anelectric double layer capacitor and a fuel cell because an electrolytesolution penetrates well into the electrode, bringing good liquidcommunication. In addition, since the pores have a uniform and finesize, a local defective structure such as a large pore may not beproduced even if the thickness of the electrode is made thin. This isadvantageous for making a fuel cell or the like thinner.

[0251] In order to manufacture a porous carbon electrode having abicontinuous structure such as an OBDD structure or Gyroid structure,the volume fraction of one polymer phase in a block copolymer should beset to 20 to 80%, more preferably 45 to 7.5%, more preferably 55 to 75%,and still more preferably 60 to 70%. In particular, it is preferablethat the volume fraction of one polymer phase be set to 62 to 67% in thecase of OBDD structure. An OTDD structure has a third continuous phaseformed at the interface of the OBDD structure. The OTDD structure can beformed from a triblock copolymer consisting of three kinds of polymerchains. In the case where the OTDD structure is formed, the volumefraction of the third phase should be set to 40 to 70%, more preferably45 to 55%. At the same time, (the volume fraction of the A phase)/(thevolume fraction of the B phase) should be set to 0.7 to 1.3, preferably0.9 to 1.1, more preferably 1.

[0252] The porous carbon electrode manufactured from a block copolymerhaving a structure having micro polymer phases has a three-dimensionalnetwork structure different from that of the conventional porousstructure manufactured by sintering fine particles. A three-dimensionalnetwork structure manufactured from a structure having micro polymerphases has correlation distances at both 2{square root}{square root over(3)} times and 4 times a radius of gyration of cross section ofconstituent microdomains. The correlation distance can be measured by,for example, X-ray small-angle scattering measurement, neutronscattering measurement and light scattering measurement or the like. Aprimary scattering peak between microdomains appears at the positionwhere the radius of gyration of cross section of constituentmicrodomains is doubled. In the case of the three-dimensional networkstructure shown in a conventional fine particle sintered body,scattering peaks of high order between particles appear at the positionsof {square root}{square root over (2)} times and {square root}{squareroot over (3)} times with respect to the double the radius of gyrationof cross section. On the other hand, in the case of thethree-dimensional network structure of the present invention, scatteringpeaks of high order appear at the positions of {square root}{square rootover (3)} times and 2 times.

[0253] The three-dimensional network structure manufactured from astructure having micro polymer phases is more regular and has lessstructural defects compared to the three-dimensional network structureshown in a conventional fine particle sintered body. When such a porouselectrode exhibits a regular three-dimensional network structure is usedin a secondary battery and capacitor, excellent charge-and-dischargecharacteristics and repeating characteristics can be given. Even whenthe electrode is used in a fuel cell, good output characteristics can begiven. Incidentally, change in molecular weight of a block copolymer orgraft copolymer can freely control the pore size of a porous moldedproduct, making it possible to manufacture a porous electrode adequatefor the purpose.

[0254] A porous structure constituted by a hole-conductive orelectron-conductive polymer, such as polyaniline, polyparaphenylene,polythiophen and polypyrrole, can be used as an electrode for anelectrochemical element such as an electrochromic element. These porousstructures can also be used as an electrode for a lithium ion secondarybattery, an electric double layer capacitor and a fuel cell.

[0255] An example in which a porous carbon electrode of the presentinvention is applied to a direct methanol fuel cell will be described.The direct methanol fuel cell uses a carbon electrode having athree-layered structure of a methanol-permeating layer, amethanol-evaporating layer and a catalytic layer, in which optimum poresizes are different for carbon electrode in each layer. It is difficultto form a multilayered carbon electrode, in which pore sizes areprecisely controlled in each layer, with a conventional carbon cloth orcarbon particle-coating film. On the other hand, with the porous carbonelectrode formed from a block copolymer having a thermally decomposablepolymer and a carbon precursor polymer, adjusting the molecular weightsof the polymers can control pore sizes precisely as already described.In addition, such a carbon electrode has very uniform pores and hardlyhas defects such as larger pores, so that the electrode can be madethinner, which enables to make the entire thickness of the cell thinner.

[0256]FIG. 7 shows a conceptual diagram of a direct methanol fuel cell.As shown in FIG. 7, formed on the anode (fuel gas) side of the cell is amultilayered-structure of the anode catalytic electrode 11, thefuel-evaporating layer 12 and the fuel-permeating layer 13, each ofwhich is porous, and formed on the cathode (liquid fuel) side of thecell is a laminate of the cathode catalytic electrode 14 and thewater-holding gas channel 15, each of which is porous, and further theelectrolyte film 16 made of a proton conductor is interposed between theanode catalytic electrode 11 and cathode catalytic electrode 14.

[0257] It is preferable to set the pore size of the outermostfuel-permeating layer 13 and water-holding gas channel 15 to 0.1 μm to10 μm. If the pore size is too small, permeability or penetratingproperty is deteriorated, whereas, if the pore size is too large, it isimpossible to make the cell thinner. It is preferable to set the poresize of the fuel-evaporating layer 12 to 50 nm to 200 nm, and those ofthe anode catalytic electrode 11 and the cathode catalytic electrode 14to 10 to 100 nm. In any member, if the pore size is too large, theliquid fuel is likely to soak into the member, whereas, if the pore sizeis too small, penetrating property of the fuel gas is deteriorated. Inany layers, 60% or more, more preferably 70% or more of pore content ispreferred. It is preferable to set the thickness of the fuel-evaporatinglayer 12, anode catalytic electrode 11 and cathode catalytic electrode14 to 1 to 10 μm. If the thickness is too small, crossover of the fuelgas is increased, which lowers efficiency. If the thickness is toolarge, mass transfer in the cell is inhibited, so that high outputcurrent density cannot be given. As the electrolyte film 16,fluoropolymer having a general sulfonic group, polybenzimidazole, ametal oxide or the like can be employed.

[0258] Noble metal particles are loaded in the electrodes: Pt particlesor the like for the anode catalytic electrode 11, and Ru particles orthe like for the cathode catalytic electrode 14. Such a particle-loadedporous electrode can be manufactured as follows. For example, a salt orcomplex of a noble metal is mixed with a block copolymer, followed byforming a structure having micro polymer phases, and then the blockcopolymer is made porous, during which the block copolymer is affectedwith formalin or fired in hydrogen or inert gas atmosphere, therebyproducing noble metal particles.

[0259] It is also possible to use a method in which a film made of ablend of an A-B block copolymer including a metal particle and an A-Bblock copolymer is formed, followed by forming a structure having micropolymer phases, and then the film is made porous. The method makes itpossible to segregate the metal particles covered with polymer on theinterface between the A polymer phase and B polymer phase on theoccasion of formation of the structure having micro polymer phases. Whenthe structure is made porous, the metal particles can be locallydistributed on the surface of the remained polymer phase. Such acatalyst electrode can exhibit high catalytic ability, since it has ahigh specific surface area and a high catalyst density with evendistribution.

[0260] In the present invention, a porous carbon structure can also bemanufactured by the following method. This method comprises steps of:mixing a precursor of thermosetting resin, a surfactant, water and oil,thereby preparing a microemulsion; curing the precursor of thermosettingresin in colloidal particles dispersed in the microemulsion; removingthe surfactant, water and oil from the colloidal particles, therebyforming porous structures of cured thermosetting resin; and carbonizingthe porous structures to form porous carbon structures.

[0261] As the precursor of thermosetting resin, phenol derivatives,resorcinol derivatives, furfuryl alcohol or the like can be employed. Across-linking agent such as titanium trichloride, boric acid or the likemay be added, if desired. As the oil, a hydrophobic solvent such asisooctane, hexane, petroleum ether or the like can be employed.

[0262] Examples of the surfactant include: a block copolymer or graftcopolymer consisting of a hydrophilic polymer chain and hydrophobicpolymer chain such as a block copolymer of polypropylene oxide andpolyethylene oxide; polyethylene oxide to which terminal a long-chainalkyl group is introduced such as polyoxyethylene lauryl ether; ananionic surfactant comprising a long-chain alkyl group to which terminala sulfonate, phosphate or carboxylate is introduced such as sodiumdodecylbenzenesulfonate; a cationic surfactant such as a long-chainammonium salt, a long-chain pyridinium salt or a long-chain imidazoliumsalt, for example, cetyltrimethylammonium chloride,cetyldimethybenzyl-ammonium chloride and cetylpyridinium bromide; afluorine-based surfactant.

[0263] In the colloidal particles dispersed in the microemulsion, astructure having micro polymer phases comprising the precursor ofthermosetting resin and the surfactant is formed. The structure havingmicro polymer phases has a relatively large size of several tens ofnanometers to several tens of micrometers, and can be formed into astructure of dot, lamella, cylinder or three-dimensional network or amixed structure thereof. Therefore, when the precursor of thermosettingresin in the colloidal particles is cured, then the surfactant, waterand oil are removed from the colloidal particles to form porousstructures of cured thermosetting resin, and then the porous structuresare carbonized, a porous carbon structures having relatively large porescan be manufactured.

[0264] In addition, when the structure having micro polymer phasesrelatively large in size which is formed using a surfactant and thestructure having micro polymer phases of the order of sub-nanometer orso are combined, it is possible to form a porous carbon structure whosestructure is controlled hierarchically in the range of sub-nanometer toseveral tens of micrometers. Typically, it is possible to provide aporous carbon structure of a spherical particle of several tens ofmicrometers in which pores of several micrometers are formed and furtherpores of several tens of nanometers or less are contained. When such aporous carbon structure is applied to a lithium ion secondary battery oran electric double layer capacitor, the nanopores of sub-nanometer serveas occlusion sites for lithium and absorption sites for ions, and thepores having a larger size serve to permeate an electrolyte solutionwell. Therefore, it makes possible to improve charge-and-dischargerepeating characteristics and output current density.

[0265] In the above method, when a microemulsion is prepared using acarbon precursor as a surfactant along with adding a metal oxide gel, acomposite of the surfactant and metal oxide gel is formed by removingthe solvent, and then the composite is fired, a composite consisting ofcarbon and metal oxide gel can be formed. This method has an advantagethat nanopores in the carbon are retained well by the metal oxide gel.If desired, the metal oxide gel may be removed by means of acid oralkali.

[0266] When a low-molecular weight surfactant having a hydrophobic groupconsisting of a long-chain alkyl group is used as a surfactant in theabove method, it is possible to manufacture a porous carbon structure inwhich cylindrical nanopores of uniform pore size, in the range ofsub-nanometer to several nanometers or so, are arranged in a honeycombconfiguration. An average pore size of the pores is preferred to be 0.1to 10 nm, more preferably 0.3 to 5 nm. Examples of the low-molecularweight surfactant include: an anionic surfactant comprising a long-chainalkyl group to which terminal a sulfonate, phosphate or carboxylate isintroduced such as sodium dodecylbenzenesulfonate; and a cationicsurfactant such as a long-chain ammonium salt, a long-chain pyridiniumsalt or a long-chain imidazolium salt, for example,cetyltrimethylammonium chloride, cetyldimethybenzyl-ammonium chlorideand cetylpyridinium bromide; a fluorine-based surfactant. When thehoneycomb porous carbon is employed as the carbon negative electrode ofa lithium ion secondary battery, nanopores is efficiently occluded bylithium, making it possible to achieve high capacity. When the honeycombporous carbon is employed as the carbon electrode of an electric doublelayer capacitor, it is possible to increase capacity if the size ofnanopores is formed as small as the ionic radius of electrolyte. Thehoneycomb porous carbon also has high absorption ability for a gas suchas hydrogen.

[0267] In the above method, when a surfactant having two or morelong-chain alkyl groups is employed, a fibrous or acicular carbonstructure can be manufactured. Such a carbon structure can be employedas a gas absorption material, or filler for imparting conductivity orreinforcing. The acicular carbon can suitably used for the emitter ofFED.

[0268] When a perylene derivative is used as a carbon precursor in theabove method, acicular carbon or honeycomb porous carbon can bemanufactured. An example of the perylene derivative includes9,10-dosubstituted peryleneimide in which a long-chain alkyl grouphaving an ionic group or hydrophilic group such as a hydroxyl group,carboxyl group, sulfonic acid group at a terminal, or a polyether groupsuch as oligoethylene oxide group is introduced. When the perylenederivative is employed, formed is a structure in which columns formed bythe perylene skeletons and columns of substituents such as a long-chainalkyl group or polyether group are alternately arranged. When thestructure is fired, columns of substituents are selectively evaporated,thus acicular carbon or honeycomb porous carbon can be provided. In thismethod, a metal oxide gel such as a silica sol may be used together. Inthe case where a nanostructure of a carbon precursor in the presence ofa surfactant in a liquid phase, performing supercritical drying ispreferred because the nanostructure is not destroyed during drying.

[0269] A case where a porous structure of the present invention isapplied to a precise filter in a sheet form or hollow fiber form will bedescribed. Such a filter can be manufactured in the following manner.First, using a pattern forming material comprising a block copolymercontaining a polymer chain that can be decomposed by energy beamirradiation, a sheet or a hollow fiber is manufactured by casting ormelt extrusion using a mouthpiece. Alternatively, the pattern formingmaterial may be applied by dip coating to the surface of a tubecomprising a homopolymer that can be decomposed by energy beamirradiation. Then, if required, annealing is performed to form aphase-separated structure in the film. The phase-separated structure ispreferred to have a continuous phase structure such as a cylindricalstructure, bicontinuous structure, etc., in which the bicontinuousstructure is particularly preferable in view of film strength.Bicontinuous structure includes an OBDD structure, a Gyroid structure, aT-surface structure, lamella catenoid structure, or the like. The OBDDstructure or Gyroid structure is particularly preferable because of lowflow resistance. The sheet or hollow fiber, in which the phase-separatedstructure is formed in such a manner, is irradiated with an electronbeam, thereby decomposing one polymer phase in the phase-separatedstructure. Thereafter, the sheet or hollow fiber is etched tomanufacture a filter in a sheet form or hollow fiber form.

[0270] The porous structure constituting the filter formed of a patternforming material of the present invention is preferred to have anaggregated structure of domains each having a radius of gyration of 50μm or less having a periodical porous structure comprising unit cellseach having a radius of gyration of 10 to 500 nm. Among periodicalporous structures, preferred is one having continuous pores formed byremoving at least one phase in a bicontinuous phase-separated structure,and particularly preferred is a porous structure formed by removing atleast one phase in a OBDD structure or Gyroid structure. Although thereis not any particular limitation with respect to the pore size, itshould preferably be in the range of 5 to 200 nm, more preferably 10 to50 nm. If the pore size is too small, flow resistance will be increased,which makes it impossible to use the filter practically. If the poresize is too large, dispersion of pore size distribution will beincreased, which makes it also impossible to use the filter practically.

[0271] The filter according to the present invention is more preferredto have an asymmetrical structure. Specifically, preferred is anasymmetrical film in which a thin filter layer consisting of a patternforming material of the present invention is formed on a relativelythick, porous film having pores large in size. Such an asymmetricalstructure can improve mechanical strength as well as reduce flowresistance. The thick, porous film having large-size pores can bemanufactured as follows. For example, using a blend of homopolymers eachhaving the same structure as each polymer chain constituting the patternforming material of the present invention, a sheet or a hollow fiber ismanufactured, and then at least one homopolymer is removed to form aporous film. In order to remove the homopolymer, it is possible to usemethods of: simple extraction with a solvent; selective etching by RIE;irradiation with an energy beam such as an electron beam and subsequentextraction with a solvent or thermal decomposition/evaporation. Then, apattern forming material according to the present invention is formed onthe porous film by dip coating. Thereafter, using a similar method tothat described above, a filter in a sheet form or hollow fiber formhaving an asymmetrical structure is manufactured.

[0272] Another method may be used in which a pattern forming material isformed on a tube consisting of a blend of homopolymers by dip coating,and then the tube is irradiated with energy beam and etched, therebyforming simultaneously a relatively thick porous film having large poresize of 0.5 to 5 μm or so and a thin filter layer to provide anasymmetrical structure, which is very effective in improving apermeation rate.

[0273] The filter of the present invention can be suitably used as afiltration membrane, a dialysis membrane, a gas separation membrane, areverse osmosis membrane, an ultrafiltration membrane, a microfiltrationmembrane or a blood purification membrane. In most of theseapplications, the filter is used in the form of filter module.

[0274] A case where a porous structure of the present invention isapplied to an ultrafine fiber of the order of nanometers having athickness of 10 to 100 nm, or to a porous fiber having pores of theorder of nanometers will be described. These ultrafine fiber and porousfiber can be manufactured, for example, in the following manner. First,using a pattern forming material comprising a block copolymer having apolymer chain that can be decomposed by energy beam irradiation, aprecursor fiber having a diameter of 10 to 100 μm is manufactured bymelt extrusion using a mouthpiece. The precursor fiber may be woven intoa fabric. Then, if required, annealing is performed to form aphase-separated structure in the fiber. The phase-separated structure ispreferred to have a continuous phase structure such as a sea-islandstructure, a cylindrical structure, a lamella structure or abicontinuous structure. The precursor fiber or fabric in which thephase-separated structure is formed in such a manner is irradiated withan energy beam selected especially from an electron beam, γ-ray or X-rayso as to decompose one phase in the phase-separated structure, followedby etching, thus an ultrafine fiber or porous fiber is provided.

[0275] The relationship between the phase-separated structure of thepattern forming material and the ultrafine fiber or porous fiber to bemanufactured is as follows. In the case of the sea-island structure, aporous fiber having closed cells is formed. In the case of thecylindrical structure, an ultrafine fiber having a thickness of theorder of nanometers having a diameter of 10 to 200 nm is formed. In thecase of the lamella structure, an ultrafine fiber in a form of thinpiece having a thickness of 10-200 nm is formed. In the case of thebicontinuous structure, a porous fiber in which unit cells of 10 to 200nm in size are periodically arrayed is formed.

[0276] These ultrafine fiber and porous fiber may contain, as alreadydescribed, a plasticizer, an antioxidant, a light stabilizer, a coloringagent (dye or pigment), an antistatic agent, a conductive agent, alubricant, a release agent, a flame retardant, an auxiliary flameretardant, etc.

[0277] The ultrafine fiber and porous fiber as well as a fabric preparedfrom these fibers has a large surface area, so that they can be used forvarious filters, a carrier medium for bacteria, a deodorant, anabsorption material, a wiping material, a water-repellent, etc. Inaddition, the fabric manufactured from the fiber of the presentinvention has texture and pleasant feeling that cannot be found in theconventional fabric.

[0278] In the present invention, a capacitor having a high capacity canbe manufactured. The method comprises the steps of: forming a film madeof a blend of a polymer including a metal particle and a block copolymeror graft copolymer; allowing the film to form a lamella structure havingmicro polymer phases and segregating the metal particles covered withthe polymer in a central portion of each polymer phase in the lamellastructure; and aggregating the metal particles to form a metal layer inthe central portion of each polymer phase in the lamella structure.

[0279] The method will be described with reference to FIGS. 8A to 8C. Inthese figures, the numeral 21 represents the A-B block copolymer, thenumeral 22 represents the A or B homopolymer, and the numeral 22represents the metal particle. First, the A-B block copolymer, A polymerincluding the metal particle and B polymer including the metal particleare blended. Use is a block copolymer having a composition ratio in therange of 70:30 to 30:70, preferably 55:45 to 45:55, so that it forms alamella structure. The material is dissolved in a solvent, followed bycasting slowly. Preferred solvent is one having a low boiling point suchas THF, acetone, and toluene. The surface of the cast film isplanarized, and then the film is extended with a roller so as to give athickness of 0.1 to 1 mm or so. The film is referred to as a first film.

[0280] Further, the blend of the A homopolymer and A homopolymerincluding a metal particle is dissolved in a solvent to manufacture acast film. The film is referred to as a second film. Likewise, the blendof the B homopolymer and B homopolymer including a metal particle isdissolved in a solvent to manufacture a cast film. The film is referredto as a third film.

[0281] The second film, the first film and the third film are laminatedin this order, followed by annealing in an oven. A lamella structure isformed through microphase separation, thus the metal particle coveredwith the A homopolymer is segregated on the A phase, and the metalparticle covered with the B homopolymer is segregated on the B phase,respectively, in which the metal particles are present in the centralportion of each polymer phase in the lamella structure. Next, when thetemperature is raised, the main chain of the polymer covering the metalparticle is broken, thus the metal particles are aggregated to form acontinuous metal film. In practice, it is assumed that migration andaggregation of two metal particles take place simultaneously during theannealing. Metal thin films are formed on the both surfaces of themanufactured film by sputtering to form electrodes, and then the film iscut into an arbitrary size.

[0282] The method can easily form a lamellar structure having uniformintervals. Since the microphase separation of the block copolymer isutilized, a lamella structure in which a number of layers arealternately laminated can be manufactured by only annealing. At thattime, the metal can be arranged in the center portion of the layersformed via microphase separation. In addition, the lamellar structuremay not cause short-circuit between metal layers. The method can makethe distance between the opposite electrodes in capacitor very short aswell as hold the electrodes in an even spacing. Therefore, the capacitorcan accumulate many charges in a small volume, thus it exhibits veryhigh performance compared to the conventional capacitor.

EXAMPLES

[0283] Hereinafter, the present invention will be specifically describedbased on examples. It should be noted that the present invention is notlimited to these examples.

Synthesis Example

[0284] A diblock copolymer (1) of polystyrene (PS) and polymethylmethacrylate (PMMA) is synthesized by living anion polymerization.Molecular sieves and activated alumina are added to polystyrene monomerand polymethyl methacrylate monomer, respectively, followed by leavingto stand for two days to remove water and an inhibitor. These monomersare distilled under reduced pressure, and then the atmosphere isreplaced with argon gas. Dehydrated THF (Wako Junyaku Co., Ltd.) isprepared as a reaction solvent to which metallic sodium is added as adehydrating agent, and then reflux is performed for two days. As apolymerization initiator, sec-butyl lithium (Kanto Kagaku Co., Ltd.) isemployed.

[0285] As a polymerization apparatus, a pressure reactor (Taiatsu GlassCo., Ltd.) is employed. The reaction is carefully performed under apressurized argon atmosphere of 4 atm so as to prevent outside air fromentering the reaction system. While flowing argon, the dehydrated THFand polymerization initiator are added. Then, the reaction system iscooled to −78° C. with dry ice/ethanol. A small quantity of styrenemonomer is added to the reaction system. After confirming that thereaction solution turned into orange color, the reaction is continuedfor 30 minutes. A small quantity of the reaction solution is taken outto measure a molecular weight by gel permeation chromatography (GPC),and on the basis of the molecular weight measured, the quantity ofstyrene monomer to be added for obtaining a polystyrene block having adesired molecular weight is calculated. Based on the calculation, astyrene monomer is added to the reaction system and the reaction isperformed for 30 minutes. A small quantity of the reaction solution istaken out, and it is confirmed by GPC that a desired molecular weight isobtained. Thereafter, a small quantity of 1,1′-diphenylethylene isadded, and then a requisite quantity of methyl methacrylate monomer toobtain a polymethyl methacrylate block having a desired molecular weightis added dropwise to the reaction system and the reaction is performedfor 30 minutes. A small quantity of the reaction solution is taken out,and it is confirmed by GPC that a desired molecular weight is obtained.After a small quantity of methanol is added dropwise to terminate thereaction, the reactor is opened. The reaction solution is dropped tomethanol for reprecipitation, followed by filtration and drying, therebyto obtain the diblock copolymer (1).

[0286] The molecular weight of each block constituting the diblockcopolymer (1) is 65,000 for polystyrene, and 13,200 for polymethylmethacrylate. Further, the molecular weight distribution (Mw/Mn) is1.04.

[0287] In the following examples, there are some cases that a diblockcopolymer of PS-PMMA other than the diblock copolymer (1) may beemployed. Also, each diblock copolymer is synthesized by living anionpolymerization in the same manner as the aforementioned synthesisexample except that the quantities of styrene monomer and methylmethacrylate monomer are changed.

Example 1

[0288] Two wt % of the diblock copolymer (1) is dissolved in propyleneglycol monoethyl ether acetate (PGMEA), followed by filtering thesolution, and then an SiO substrate is spin-coated with the solution at2,500 rpm. The substrate is heated to 110° C. for 90 seconds toevaporate the solvent. Thereafter, the substrate is placed in an oven,and annealing is performed in a nitrogen atmosphere at 210° C. for 10minutes, subsequently at 135° C. for 10 hours. Since the temperature of210° C. is just below a temperature that decomposition of the acrylicblock takes place, the short time annealing enables to flatten the filmwith dissipating hysteresis after spin-coating. Further, the annealingat the temperature of about 135° C. enables to promote microphaseseparation of the diblock copolymer efficiently, so that a film havingmicro polymer phases is formed.

[0289] Reactive ion etching (RIE) is performed to the sample under theconditions of CF₄, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave. Under the etching conditions, since the ratio of etchrates between PS and PMMA constituting the film having micro polymerphases is 1:4 or more, PMMA is selectively etched and further theexposed underlayer is etched by use of the remaining PS pattern as amask. Thereafter, ashing is performed to the sample under the conditionsof O₂, 0.01 Torr, 150 W of progressive wave, and 30 W of reflected waveto remove the organic substance (the mask formed of PS).

[0290] As a result, holes having a diameter of 12 nm and a depth of 15nm are formed over the entire surface of the SiO substrate having adiameter of 3 inches at a density of about 700/μm² and at approximatelyregular intervals. The substrate can be used as a substrate for a harddisk.

[0291] In addition, a film having micro polymer phases is formed in thesame manner as described above except that 10 wt % of dioctyl phthalateas a plasticizer is added to the diblock copolymer (1) and the heattreatment conditions are changed to at 210° C. for 10 minutes,subsequently at 135° C. for one hour, and RIE is performed under thesame conditions as described above. As a result, a pattern of holes canbe formed on the substrate similar to those described above. Thus, it ispossible to greatly shorten the heat treatment time by adding theplasticizer to the diblock copolymer.

Example 2

[0292] A film having micro polymer phases is formed on a glass substratein the same manner as described in Example 1. The film having micropolymer phases is irradiated with an electron beam over the entiresurface under the conditions of an accelerating voltage of 50 kV and anexposure dose of 100 μC/cm², thus the main chain of the PMMA is cut. Thefilm having micro polymer phases is developed with a developer (3:7mixed solution of MIBK and IPA) for an electron beam resist for 60seconds, followed by rinsing with IPA, thus the PMMA whose main chain iscut by electron beam is removed. Then, using a pattern mainly consistingof remaining PS as a mask, the substrate is etched with hydrofluoricacid for one minute. Thereafter, the substrate is subjected to anultrasonic washing in acetone, thus the remaining mask is removed.

[0293] As a result, holes having a diameter of 15 nm and a depth of 12nm are formed over the entire surface of the glass substrate at adensity of about 700/μm² and at approximately regular intervals. Bymaking use of this method, the whole steps can be performed by wetprocesses. As in the case of Example 1, the substrate can be used as asubstrate for a hard disk.

[0294] When the pattern formation is performed in the same manner asdescribed above except that the substrate is irradiated with X-rayhaving a wavelength of 0.154 nm under an exposure dose of 1 J/cm² inplace of the electron beam irradiation, holes having a diameter of 15 nmand a depth of 12 nm are formed over the entire surface of the glasssubstrate at a density of about 700/μg and at approximately regularintervals.

Example 3

[0295] Using a diblock copolymer (2) (polystyrene: Mw=10,600, polymethylmethacrylate: Mw=35,800; Mw/Mn=1.07), a film having micro polymer phasesis formed on a magnetic film formed on a substrate having a diameter of3 inches in the same manner as described in Example 1. The film havingmicro polymer phases is irradiated with an electron beam to cut the mainchain of PMMA. The film having micro polymer phases is developed with adeveloper for electron beam resist, thus PMMA whose main chain is cut byelectron beam is removed. Then, using a pattern mainly consisting ofremaining PS as a mask, the substrate is etched with hydrochloric acidfor one minute. Thereafter, the substrate is subjected to an ultrasonicwashing in acetone, thus the remaining mask is removed.

[0296] As a result, projections of magnetic film having a diameter of 15nm and a height of 12 nm are formed over the entire surface of thesubstrate at a density of about 650/μg and at approximately regularintervals. By making use of this method, a magnetic film can be leftremained in an island configuration by directly processing the film inwet processes.

Example 4

[0297] A quartz substrate is spin-coated with a polystyrene film havinga thickness of 500 nm as a lower pattern transfer film, on which analuminum film having a thickness of 10 nm is deposited as an upperpattern transfer film. The aluminum film is spin-coated with diblockcopolymer (3) (polystyrene: Mw=144,600, polymethyl methacrylate:Mw=70,700; Mw/Mn=1.07) having a thickness of 80 nm. Then, annealing isperformed in the same manner as in Example 1 to form a film having micropolymer phases.

[0298] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave, thus PMMAin the film having micro polymer phases is etched selectively andfurther the aluminum film is etched by use of remaining PS pattern as amask. Thereafter, ashing is performed to the sample under the conditionsof O₂, 0.01 Torr, 150 W of progressive wave, and 30 W of reflected waveto remove the mask consisting of remaining PS and the polystyrene filmexposed at the portions where the aluminum film has been etched. RIE isperformed again to the sample under the conditions of CF₄, 0.01 Torr,150 W of progressive wave, and 30 W of reflected wave, thus the upperaluminum film and the exposed portions of the quartz substrate isetched. Ashing is performed again to the sample under the conditions ofO₂, 0.01 Torr, 150 W of progressive wave, and 30 W of reflected wave toetch the remaining polystyrene.

[0299] As a result, holes having a very high aspect ratio, i.e., adiameter of 110 nm and a depth of 1200 nm are formed over the entiresurface of the quartz substrate at a density of 35/μm².

Example 5

[0300] An SiO₂ film having a thickness of 500 nm is formed on a siliconwafer, and then the SiO₂ film is coated with a toluene solution ofpolysilane (Mw=12000, x=0.4) represented by the following chemicalformula, followed by baking to form a pattern transfer film consistingof polysilane having a thickness of 100 nm.

[0301] The pattern transfer film is coated with a diblock copolymer (4)(polystyrene: Mw=12,000, polymethyl methacrylate: Mw=28000), followed bybaking at 90° C. for two minutes to form a 40 nm-thick film having micropolymer phases.

[0302] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave, thus PMMAin the film having micro polymer phases is etched selectively. Then, thepolysilane film is etched by use of the remaining PS pattern as a maskunder the conditions of HBr flow rate of 50 sccm, vacuum degree of 80mTorr and excitation power of 200 W to transfer the pattern. Since themask consisting of PS is left remained on the remaining polysilane film,it is found that there is a sufficient etch rate ratio between them.Then, by use of the pattern of polysilane film as a mask, the SiO₂ filmis etched under the conditions of C₄F₈ flow rate of 50 sccm, CO flowrate of 10 sccm, Ar flow rate of 100 sccm, O₂ flow rate of 3 sccm,vacuum degree of 10 mTorr, and excitation power of 200 W to transfer thepattern. Since the polysilane film is left remained on the remainingSiO₂ film, it is found that the polysilane film is sufficient etchresistance. The remaining polysilane film can be easily removed with anaqueous organoalkali solution or a diluted hydrofluoric acid solution.

Example 6

[0303] A gold electrode is deposited on 10-inch glass substrate used fora substrate of a field emission display, an SiO₂ film as a lower patterntransfer film is applied to the entire surface of the gold electrode,and further an aluminum film having a thickness of 20 nm as an upperpattern transfer film is deposited on the lower pattern transfer film.Then, a diblock copolymer (5) (polystyrene: Mw=127,700, polymethylmethacrylate: Mw=1,103,000; Mw/Mn=1.30) and polystyrene homopolymer(Mw=45000, Mw/Mn=1.07) are blended together at a weight ratio of 21:79,then the blend is dissolved in ethylcellosolve acetate (ECA) at a solidcontent of 5 wt %, followed by filtration. The aluminum film isspin-coated with the solution, followed by drying at 110° C. to form apolymer film having a thickness of 970 nm. In the same manner as inExample 1, the substrate is placed in an oven, and annealing isperformed in a nitrogen atmosphere at 210° C. for 10 minutes,subsequently at 135° C. for 10 hours to form a film having micro polymerphases.

[0304] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave, thus PMMAin the film having micro polymer phases is etched selectively andfurther the aluminum film is etched using the remaining PS pattern as amask to transfer the pattern. Using the pattern of PS and the pattern ofaluminum film as a mask, exposed portions of the SiO film are etchedwith hydrofluoric acid to transfer the pattern. Since the pattern ofaluminum film is covered with a pattern of PS, it is not damaged.Thereafter, ashing is performed with an O₂ asher to remove the remainingPS pattern.

[0305] As a result, holes having a diameter of about 840 nm can beformed at a density of about 23000 per pixel of 300 μm×100 μm.Distribution of hole size is found uniform within the range of ±10%.This is attributed to the uniformity in molecular weight of the diblockcopolymer. Since the diblock copolymer exists in the sea of styrenehomopolymer in the polymer film employed as a mask, the arrangement offormed holes is found random. Therefore, it is advantageous inapplication to a display to prevent an interference fringe due toregular arrangement of electrodes.

[0306] The structure formed by the method in this example can be appliedto a field emission display (FED) as well as a gate electrode of aporous gate transistor display, etc.

[0307] In addition, a film having micro polymer phases is formed in thesame manner as described above except that 10 wt % of dioctyl phthalateis added as a plasticizer to the blend of diblock copolymer andpolystyrene homopolymer and the heat treatment conditions are changed toat 210° C. for 10 minutes, -subsequently at 135° C. for one hour, andRIE is performed under the same conditions as described above. As aresult, a pattern of holes can be formed on the substrate similar tothose described above. Thus, it is possible to greatly shorten the heattreatment time by addition of the plasticizer.

Example 7

[0308] A 10 wt % solution of a diblock copolymer (6) (polystyrene:Mw=135,000, PMMA: Mw=61,000, Mw/Mn=1.10) in THF is poured in a TeflonPetri dish, which solution is allowed to dry slowly over 14 days in adesiccator to form a film. The thickness of the film is 0.2 mm. The filmis further vacuum dried for 3 days. An ultra-thin film is cut out ofthis film to observe with a transmission electron microscope. As aresult, it is confirmed that the PS phase and the PMMA phase arerespectively formed continuously into a three-dimensional bicontinuousstructure.

[0309] The film is irradiated with an electron beam under the conditionsof accelerating voltage of 2 MV and exposure dose of 10 kGy, and thenthe film is developed with a developer for electron beam resist, whichis reduced is solubility of PS by addition of IPA, followed by vacuumdrying. An ultra-thin film is cut out of the film to observe again witha transmission electron microscope. As a result, it is confirmed thatthe PMMA phase is removed and the PS phase is formed into a spongycontinuous structure. It is confirmed that the structure is almost thesame as the three-dimensional bicontinuous structure observed first.

[0310] The film is constituted by a PS phase that is three-dimensionallycontinued with interposing regularly continued cells of the order ofnanometers. Such a structure can be applied to a separator for a polymerbattery or capacitor.

Example 8

[0311] A diblock copolymer (1) is dissolved by 1 wt % in methylenechloride, followed by filtering, and then 1 wt % based on the weight ofthe polymer of tetrabutylammonium hexachloroplatinate (IV) is added. Thesolution is cast on a SiO substrate having a diameter of 3 inches toform a film having a thickness of 20 nm. The substrate is heated at 110°C. for 90 seconds to evaporate the solvent. Then, the substrate isplaced in an oven and subjected to annealing at 150° C. for 3 hours in anitrogen atmosphere to form a film having micro polymer phases. At thattime, tetrabutylammonium hexachloroplatinate (IV) is segregated in PMMA.After the film having micro polymer phases is rinsed with formaldehydereducing solution, the film is again subjected to annealing at 200° C.for one hour, thereby reducing the tetrabutylammoniumhexachloroplatinate (IV) to platinum.

[0312] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave, thus PMMAis etched selectively and further the underlying SiO substrate is etchedby use of the remaining PS pattern as a mask. Thereafter, ashing isperformed under the conditions of O₂, 0.01 Torr, 150 W of progressivewave, and 30 W of reflected wave to remove the remaining PS mask.

[0313] As a result, holes having a diameter of 15 nm and a depth of 10nm are formed over the entire surface of the SiO substrate having adiameter of 3 inches at a density of about 2000/μm² and at approximatelyregular intervals. Furthermore, platinum particles are deposited at thebottoms of the holes. By making use of the substrate, a magneticmaterial, for example, can be grown over the platinum particlesdeposited at the bottoms of the holes as nuclei, and therefore thesubstrate is applicable to a substrate for a hard disk.

Example 9

[0314] A diblock copolymer (1) is dissolved in DMF by 1 wt %, followedby filtering, and then a DMF solution, in which 1 wt % based on theweight of the polymer of tetrabutylammonium hexachloroplatinate (IV) isdissolved, is added and mixed homogeneously. A DMF solution of sodiumborate hydride is added to the solution to reduce the tetrabutylammoniumhexachloroplatinate (IV), thereby precipitating platinum particleshaving an average particle size of 4 nm. A SiO substrate having adiameter of 3 inches is spin-coated with the solution to form a filmhaving a thickness of 25 nm. The substrate is heated at 110° C. for 90seconds to evaporate the solvent. Then, the substrate is placed in anoven and subjected to annealing in a nitrogen atmosphere at 200° C. for3 hours to form a film having micro polymer phases. At that time,platinum particles are segregated in PMMA.

[0315] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave, thus PMMAis selectively etched and further the underlying SiO substrate is etchedby use of the remaining PS pattern as a mask. Thereafter, ashing isperformed under the conditions of O₂, 0.01 Torr, 150 W of progressivewave, and 30 W of reflected wave, thus the remaining PS mask is removed.

[0316] As a result, holes having a diameter of 17 nm and a depth of 10nm are formed over the entire surface of the SiO substrate having adiameter of 3 inches at a density of about 2000/μm² and at approximatelyregular intervals. Furthermore, platinum particles are deposited at thebottoms of the holes. By making use of the substrate, a magneticmaterial, for example, can be grown over the platinum particlesdeposited at the bottoms of the holes as nuclei, and therefore thesubstrate is applicable to a substrate for a hard disk.

Example 10

[0317] A diblock copolymer (1) is dissolved by 1 wt % in methylenechloride, followed by filtering, and then 1 wt % based on the weight ofthe polymer of tetrabromogold(III) cetylpyridinium salt is added. Thesolution is cast on a SiO substrate having a diameter of 3 inches toform a film having a thickness of 20 nm. The substrate is heated at 110°C. for 90 seconds to evaporate the solvent. Then, the substrate is placein an oven and subjected to annealing in a nitrogen atmosphere byraising the temperature from 100° C. to 200° C. over 3 hours to form afilm having micro polymer phases. As a result of the annealing, thetetrabromogold(III) cetylpyridinium salt is reduced, therebyprecipitating gold fine particles. At that time, the gold fine particlesare segregated in PMMA.

[0318] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave, thus PMMAis selectively etched and further the underlying SiO substrate is etchedby use of the remaining PS pattern as a mask. Thereafter, ashing isperformed under the conditions of O₂, 0.01 Torr, 150 W of progressivewave, and 30 W of reflected wave to remove the remaining PS mask.

[0319] As a result, holes having a diameter of 15 nm and a depth of 10nm are formed over the entire surface of the SiO substrate having adiameter of 3 inches at a density of about 2000/μm² and at approximatelyregular intervals. Furthermore, gold particles are deposited at thebottoms of the holes. It is also possible to produce platinum fineparticles in the same manner as described above. By making use of thesubstrate, a magnetic material, for example, can be grown over theplatinum particles deposited at the bottoms of the holes as nuclei, andtherefore the substrate is applicable to a substrate for a hard disk.

Example 11

[0320] Two kinds of telechelic polymers, i.e., carboxyl-terminatedpolystyrene (Mw=83,000, Mw/Mn=1.08) represented by the chemical formula(lla) is blended with amino-terminated polymethyl methacrylate(Mw=19,600, Mw/Mn=1.03) represented by the chemical formula (11b) inequal moles, and then, dissolved in PGMEA to obtain a 2 wt % solution.The polystyrene and PMMA are allowed to react with each other in thesolution to prepare a diblock copolymer. The solution is filtered, andthen applied to a SiO substrate having a diameter of 3 inches by spincoating at a rate of 2,500 rpm. The substrate is heated at 110° C. for90 seconds to evaporate the solvent. Thereafter, the substrate is placedin an oven and subjected to annealing in a nitrogen atmosphere at 210°C. for 10 minutes, subsequently at 135° C. for 10 hours to form a filmhaving micro polymer phases.

[0321] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave, thus PMMAin the film having micro polymer phases is etched selectively andfurther the underlying substrate is etched with the remaining PS patternbeing used as a mask. Thereafter, ashing is performed under theconditions of O₂, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave to remove the remaining PS mask.

[0322] As a result, holes having a diameter of 25 nm and a depth of 16nm are formed over the entire surface of the SiO substrate having adiameter of 3 inches at a density of about 1000/μm² and at approximatelyregular intervals.

Example 12

[0323] Dimethylchlorosilyl-terminated polystyrene (Mw=85,000,Mw/Mn=1.04) represented by the chemical formula (12a) is blended withhydroxyl-terminated polydimethyl siloxane (Mw=16,800, Mw/Mn=1.10)represented by the chemical formula (12b) in equal moles, to which asmall quantity of triethyl amine is added, and then the blend isdissolved in PGMEA to obtain a 2 wt % solution. In the solution,polystyrene and polydimethyl siloxane are allowed to react with eachother in the presence of trimethyl amine to produce a diblock copolymer.The solution is filtered and then, is applied to a SiO substrate havinga diameter of 3 inches by spin coating at a rate of 2,500 rpm. Thesubstrate is heated at 110° C. for 90 seconds to evaporate the solvent.Then, the substrate is placed in an oven and subjected to annealing in anitrogen atmosphere at 210° C. for 10 minutes, subsequently at 135° C.for 10 hours to forming a film having micro polymer phases.

[0324] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave. Under theetching conditions, the etch rate ratio between PS and polydimethylsiloxane comes to be 1:4 or more. As a result, only the polydimethylsiloxane in the film having micro polymer phases is selectively etched,and further the underlying SiO substrate is etched with using theremaining PS pattern as a mask. Thereafter, ashing is performed underthe conditions of O₂, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave to remove the remaining PS mask.

[0325] As a result, holes having a diameter of 25 nm and a depth of 17nm are formed over the entire surface of the SiO substrate having adiameter of 3 inches at a density of about 1000/μm² and at approximatelyregular intervals.

Example 13

[0326] A diblock copolymer of polyphenylmethyl silane-polystyrene(polyphenylmethyl silane: Mw=12,000, polystyrene: Mw=48,000, Mw/Mn=2.1)is synthesized by the method of S. Demoustier-Champagne et al. (Journalof Polymer Science: Part A: Polymer Chemistry, Vol. 31,2009-2014(1993)).

[0327] After 1.5 wt % of the diblock copolymer is dissolved in tolueneand filtered, the solution is applied to an SiO substrate having adiameter of 3 inches by spin coating at a rate of 2,500 rpm. Thesubstrate is heated at 110° C. for 90 seconds to evaporate the solvent.Then, the substrate is placed in an oven and subjected to annealing in anitrogen atmosphere at 210° C. for 10 minutes, subsequently at 135° C.for 10 hours to form a film having micro polymer phases.

[0328] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave. Under theetching conditions, the etch rate ratio between PS and polysilane comesto be 1:4 or more. As a result, only the polysilane in the film havingmicro polymer phases is selectively etched, and further the underlyingSiO substrate is etched with using the remaining PS pattern as a mask.Then, ashing is performed under the conditions of O₂, 0.01 Torr, 150 Wof progressive wave, and 30 W of reflected wave to remove the remainingPS mask.

[0329] As a result, holes having a diameter of 12 nm and a depth of 10nm are formed over the entire surface of the SiO substrate having adiameter of 3 inches at a density of about 2400/μm² and at approximatelyregular intervals.

Example 14

[0330] Using masked disilane represented by the chemical formula (14a)as a monomer and phenyl methacrylate represented by the chemical formula(14b), a diblock copolymer represented by the chemical formula (14c) issynthesized by living anion polymerization. Specifically, thepolymerization is performed in a THF solution using sec-butyl lithium asan initiator, setting the reaction temperature to −78° C. and adding themonomer successively. The diblock copolymer is found to be 70,500 inweight average molecular weight (Mw), Mw/Mn=1.2, 14,500 in molecularweight of polysilane block, and 56,000 in molecular weight of polyphenylmethacrylate block.

[0331] After 1.5% weight of the diblock copolymer is dissolved intoluene and filtered, the solution is applied to a SiO substrate havinga diameter of 3 inches by spin coating at a rate of 2,500 rpm. Thesubstrate is heated at 110° C. for 90 seconds to evaporate the solvent.Then, the substrate is placed in an oven and subjected to annealing in anitrogen atmosphere at 210° C. for 10 minutes, subsequently at 135° C.for 10 hours to form a film having micro polymer phases.

[0332] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave. Under theetching conditions, only the polysilane in the film having micro polymerphases is selectively etched, and further the underlying SiO substrateis etched with using the remaining polyphenyl methacrylate pattern as amask. Thereafter, ashing is performed under the conditions of O₂, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave to removethe remaining polyphenyl methacrylate.

[0333] As a result, holes having a diameter of 14 nm and a depth of 10nm are formed over the entire surface of the SiO substrate having adiameter of 3 inches at a density of about 2400/μm² and at approximatelyregular intervals.

Example 15

[0334] Styrene-terminated polyethylene oxide macromer represented by thechemical formula (15a) (Mw=14,100, Mw/Mn=1.04) and styrene are dissolvedin THF, to which solution AIBN as a radical initiator is added, and thenthe resultant mixture is heated in an argon atmosphere at 60° C. for 60hours for radical polymerization to synthesize a graft copolymer. Thisgraft copolymer is found to be 101,000 in weight average molecularweight (Mw), Mw/Mn=2.1, 16,400 in molecular weight of styrene chain, and84,600 in molecular weight of polyethylene oxide macromer unit.

[0335] After 2 wt % of the graft copolymer is dissolved in ethyl lactateand filtered, the solution is applied to an SiO substrate having adiameter of 3 inches by spin coating at a rate of 2,500 rpm. Thesubstrate is heated at 110° C. over 90 seconds to evaporate the solvent.Then, the substrate is placed in an oven and subjected to annealing in anitrogen atmosphere at 210° C. for 10 minutes, subsequently at 135° C.for 10 hours to form a film having micro polymer phases.

[0336] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave. Under theconditions, only the polyethylene oxide in the film having micro polymerphases is selectively etched, and further the underlying SiO substrateis etched with using the remaining PS pattern as a mask. Then, ashing isperformed under the conditions of O₂, 0.01 Torr, 150 W of progressivewave, and 30 W of reflected wave to remove the remaining PS mask.

[0337] As a result, innumerable projections having a diameter of 18 nmand a height of 10 nm are formed over the entire surface of thesubstrate.

Example 16

[0338] An electrolyte separator for electrochemical cell is manufacturedas follows.

[0339] First, a diblock copolymer is synthesized. To anhydrous THFdistilled in the presence of metallic sodium, α-styryl lithium is addedas an initiator, and isoprene and methyl methacrylate are successivelyadded, thereby synthesizing a diblock copolymer comprising apolyisoprene chain and a polymethyl methacrylate chain. The diblockcopolymer is found to be 81,000 in weight average molecular weight (Mw),Mw/Mn=1.3, and 67% in weight fraction of polyisoprene unit.

[0340] A solution of the diblock copolymer is prepared and formed into afilm by casting. The film is annealed under a nitrogen gas flow at 130°C. for 5 hours to form a structure having micro polymer phases. When thestructure having micro polymer phases is observed with TEM, a Gyroidstructure having openings of about 40 nm in size is formed.

[0341] The film having a Gyroid structure is irradiated with an electronbeam under the conditions of 2 MV in accelerating voltage and 10 kGy inexposure dose, thereby cutting the main chain of the polymethacrylatephase, and, at the same time, cross-linking the polyisoprene phase(gelation). The film is rinsed with a mixed solvent of MIBK andisopropyl alcohol (volume ratio: 3.7) to remove the polymethacrylatephase. When the film is observed with TEM, it is confirmed that the filmretains the Gyroid structure and is porous with continuous pores.

[0342] The porous film is impregnated with a 1M solution of LiClO₄(anhydride) in propylene carbonate and punched out into a disk having adiameter of 0.5 cm to provide an electrolyte-impregnated porous filmhaving a thickness of about 50 μm. The electrolyte-impregnated porousfilm is sandwiched between platinum electrodes to give a cell, which ismeasured for AC impedance using an impedance gain phase analyzer 1260(Schlumberger Instruments Co., Ltd.) at room temperature and at afrequency of 30 MHz to 0.05 Hz. Thus, ion conductivity of the cell isdetermined from a=(1/R) (d/s), where R is electric resistance of thefilm given by the measured AC impedance; s (cm²) is the area of thefilm; and d (cm) is the thickness of the film. The porous film exhibitsgood ion conductivity of 4.2 mScm⁻¹ at 25° C. The porous film holds theelectrolyte solution well, and hence, no liquid leakage occurs.

[0343] Further, an electrolyte-impregnated porous film is prepared inthe same manner as described above except that 3 wt %, based on thediblock copolymer, of silica fine particles (Tokuseal P, Tokuyama SodaCo., Ltd.) is dispersed in the solution of diblock copolymer. Theresultant porous film exhibits good ion conductivity of 4.5 mScm⁻¹ at25° C.

[0344] It is found from these results that the electrolyte-impregnatedporous film in this example has an excellent property useful for anelectrolyte separator for an electrochemical cell such as a lithium ionsecondary battery, and for a dye-sensitizing photovoltaic cell such asan electrochromic cell and a Gratzer cell.

Example 17

[0345] Using the same diblock copolymer comprising polyisoprene chainand polymethyl methacrylate chain as used in Example 16, an electrolyteseparator for electrochemical cell is manufactured by melt extrusionmolding as described below.

[0346] First, a little amount (about 1 wt % based on the polymer) of avulcanizing agent is added to the diblock copolymer, and then thecopolymer is dissolved in dimethylformamide (DMF) to form a stocksolution for extrusion molding. The viscosity of the stock solution is2400 mPaòs at 40° C. The stock solution is ejected from a sheet diehaving a rectangular nozzle of 60 μm in slit width into a 40% solutionof DMF, thereby manufacturing a diblock copolymer sheet. The sheet isannealed under a nitrogen gas flow at 130° C. for 5 hours to give astructure having micro polymer phases. Thereafter, the sheet is annealedat 150° C. for 5 hours to cross-link the polyisoprene chain. The sheetis irradiated with an electron beam under the conditions of 2 MV inaccelerating voltage and 10 kGy in exposure dose. The sheet is rinsedwith a mixed solvent of MIBK and isopropyl alcohol (volume ratio: 3.7)to obtain a porous sheet.

[0347] The porous sheet is impregnated with a 1M solution of LiClO₄(anhydride) in propylene carbonate, and then punched out in to a diskhaving a diameter of 0.5 cm to provide an electrolyte-impregnated poroussheet having a thickness of about 50 μm. When theelectrolyte-impregnated porous sheet is measured for ion conductivity ofin the same manner as in Example 16, it exhibits good ion conductivityof 4.6 mScm⁻¹.

Example 18

[0348] Using the same diblock copolymer comprising polyisoprene chainand polymethyl methacrylate chain as used in Example 16, an electrolyteseparator for electrochemical cell is manufactured by melt extrusionmolding as described below.

[0349] A mixture of the diblock copolymer added with 2 wt % of aphenol-based antioxidant (Sumilizer BP-76, Sumitomo Kagaku Kogyo Co.,Ltd.) is kneaded at 180° C. to prepare pellets. The pellets are fed toan extruder and melt at 190° C., and then ejected from a sheet diehaving a rectangular nozzle to manufacture a diblock copolymer sheet.The sheet is annealed under a nitrogen gas flow at 130° C. for 5 hours,and then irradiated with an electron beam under the conditions of 2 MVin accelerating voltage and 10 kGy in exposure dose. The sheet is rinsedwith a mixed solvent of MIBK and isopropyl alcohol (volume ratio: 3.7)to obtain a porous sheet.

[0350] The porous film is impregnated with a 1M solution of LiClO₄(anhydride) in propylene carbonate, and the punched out into a diskhaving a diameter of 0.5 cm to provide an electrolyte-impregnated poroussheet having a thickness of about 50 μm. When theelectrolyte-impregnated porous sheet is measured for ion conductivity inthe same manner as in Example 16, it exhibits good ion conductivity of4.1 mScm⁻¹.

Example 19

[0351] A hollow fiber filter is manufactured as follows.

[0352] A diblock copolymer (7) of polystyrene (PS) and polymethylmethacrylate (PMMA) (Mw=75,000, weight ratio of polystyrene unit=68%,Mw/Mn=1.03) is dissolved in propylene glycol methyl ether acetate(PGMEA) to prepare a solution. A hollow fiber made of polymethylmethacrylate is dip-coated with the solution. After being air-dried at70° C., the hollow fiber is annealed under a nitrogen gas flow at 135°C. for 10 hours. Thereafter, the hollow fiber is irradiated with anelectron beam under the conditions of 2 MV in accelerating voltage and10 kGy in exposure dose. The hollow fiber is rinsed with a mixed solventof MIBK and isopropyl alcohol (volume ratio: 3.7) to provide a poroushollow fiber. The resultant porous hollow fiber has an inner diameter of500 μm and an outer diameter of 600 μm, and the side wall thereof ismade porous to which an OBDD type phase-separated structure of 35 nm inpore size is transferred.

Example 20

[0353] A hollow fiber filter is manufactured as follows.

[0354] A polymer blend of polystyrene (Mw=51,000, Mw/Mn=1.03) andpolymethyl methacrylate (Mw=72,000, Mw/Mn=1.06) (weight ratio=6:4) isdissolved in PGMEA to prepare a solution. A hollow fiber made ofpolymethyl methacrylate is dip-coated with the solution. After beingair-dried at 70° C., the hollow fiber is annealed under a nitrogen gasflow at 135° C. for one hour to form a covering film having a thicknessof 45 μm. Further, a solution of the diblock copolymer (7) of PS-PMMA inPGMEA, which is the same as that employed in Example 19, is prepared.The above hollow fiber is dip-coated with the solution. The hollow fiberis air-dried to form a covering film having a thickness of 5 μm. Thehollow fiber is annealed under a nitrogen gas flow at 135° C. for 10hours. Thereafter, the hollow fiber is irradiated with an electron beamunder the conditions of 2 MV in accelerating voltage and 10 kGy inexposure dose. The hollow fiber is rinsed with a mixed solvent of MIBKand isopropyl alcohol (volume ratio: 3.7) to provide a porous hollowfiber. The resultant porous hollow fiber has an inner diameter of 500 μmand an outer diameter of 600 μm, and the side wall thereof has anasymmetrical film structure composed by an outer layer, to which an OBDDtype phase-separated structure of 35 nm in pore size is transferred, anda porous inner layer having continuous pores of about 0.5 to 1 μm inpore size.

Example 21

[0355] A diblock copolymer of polystyrene (PS) and poly-tert-butylacrylate (PtBA) is prepared. Then, 2 wt % of the diblock copolymer isdissolved in PGMEA. Naphthylimidyl trifluoromethane sulfonate as aphoto-acid generator is added to the solution at a ratio of 1.5 wt %based on the diblock copolymer. A glass substrate is spin-coated withthe solution, and the dried on a hot plate at 110° C. for 3 minutes toform a film having a thickness of 100 nm.

[0356] The glass substrate is set to a stepper, and then the diblockcopolymer film is exposed with an i-line (365 nm). In the exposedportions, acid is generated from the naphthylimidyl trifluoromethanesulfonate, with which acid as a catalyst the tertiary butyl group ofPtBA is decomposed, and hence the PtBA is turned into polyacrylic acid.The glass substrate is placed in an oven and subjected to annealing at160° C. for one hour, thereby forming a structure having micro polymerphases in the film.

[0357] Next, RIE with CF₄ gas is performed. The microdomains ofpolyacrylic acid can be easily etched in the exposed portions, andfurther the underlying glass substrate portion is also etched, but PS isleft unetched. In the unexposed portion, both PS and PtBA are leftunetched. As a result, a pattern of holes having a diameter of about 90nm can be formed only in the exposed portions.

Example 22

[0358] A diblock copolymer of polystyrene (PS) and polymethylmethacrylate (PMMA) is prepared. Then, 2 wt % of the diblock copolymeris dissolved in PGMEA. A glass substrate is spin-coated with thesolution and dried on a hot plate at 110° C. for 3 minutes to form afilm having a thickness of 100 nm. The glass substrate is placed in anoven and annealed in a nitrogen atmosphere at 210° C. for 10 minutes,subsequently at 135° C. for 10 hours, thereby forming a structure havingmicro polymer phases in the film.

[0359] The glass substrate is set to an electron beam irradiationapparatus (EX-8D, Toshiba Co., Ltd.) and the diblock copolymer film isexposed to an electron beam to cut the main chain of the PMMA. The filmis developed with a developer (a 3:7 mixed solution of MIBK and IPA) foran electron beam resist. In the exposed portions, PMMA whose main chainis cut is etched, but PS is left unetched. In the unexposed portions,both PS and PtBA are left unetched. Next, the glass substrate atportions exposed to outside is etched with hydrofluoric acid for oneminute using the pattern of remaining polymer as a mask. Thereafter, thesubstrate is subjected to an ultrasonic washing in acetone, therebyremoving the pattern of remaining polymer. As a result, a pattern ofholes having a diameter of about 90 nm can be formed only in the exposedportions.

Example 23

[0360] A film having micro polymer phases is formed on a 3-inch SiOsubstrate by annealing in a nitrogen gas atmosphere in the same manneras described in Example 1 except that 0.1 wt %, based on the diblockcopolymer, of a phenol-based antioxidant (Sumilizer BP-101, SumitomoKagaku Kogyo Co., Ltd.) is added to a solution of the diblock copolymer(1).

[0361] When the annealed film having micro polymer phases is measuredfor infrared absorption spectrum, chemical denaturing such as oxidationresulting from annealing is found suppressed in the film having micropolymer phases.

[0362] Thereafter, in the same manner as described in Example 1, the SiOsubstrate is etched using the film having micro polymer phases as amask. As a result, holes having a diameter of 12 nm and a depth of 18 nmcan be formed over the entire surface of the SiO substrate at a densityof about 2000/μm² and at approximately regular intervals. As comparedwith the holes of Example 1, the depth of holes formed in this exampleis deeper and dispersion of intervals between holes is reduced by half.

[0363] As described above, addition of an antioxidant can suppress theoxidative denaturing of the diblock copolymer resulting from annealing,making it possible to improve pattern-forming capability and etchingproperties of the diblock copolymer.

[0364] Further, even if annealing is performed in air atmosphere, it ispossible to form holes having a diameter of 12 nm and a depth of 18 nmover the entire surface of the SiO substrate at a density of about2000/μm² and at approximately regular intervals like the above case. Onthe other hand, in the case where a diblock copolymer containing noantioxidant is annealed in air atmosphere to form a film having micropolymer phases, the depth of holes formed in the substrate is as shallowas 10 nm and the intervals between holes are relatively uneven. Asdescribed above, when an antioxidant is added to a diblock copolymer, itis possible to form a good pattern even in air as that given undernitrogen gas flow.

[0365] Further, pattern formation is performed in the same manner asdescribed above using a phosphorus-based antioxidant such asSumilizer-P-16 and Adecastab PEP-24G; sulfur-based antioxidant such asSumilizer-TPM and Sumilizer-TP-D (all available from Sumitomo KagakuKogyo Co., Ltd.); and an HALS-type antioxidant such as Sanol LS-770(Sankyo Co., Ltd.) in place of the phenol-based antioxidant. Even whenany of these antioxidants is used, it is possible to increase the depthof the holes by about 20% and to suppress dispersion in intervalsbetween the holes as compared with those obtained in Example 1irrespective of whether the annealing atmosphere is nitrogen or air.

Example 24

[0366] A film having micro polymer phases is formed on a 3-inch SiOsubstrate and then, a pattern is formed in the same manner as describedin Example 2 except that 0.1 wt %, based on the diblock copolymer, of anester type antioxidant represented by the following chemical formula isadded to a solution of the diblock copolymer (1) and that annealing isperformed in air atmosphere. As a result, it is possible to obtain agood pattern as in the case of Example 2.

[0367] Further, pattern formation is performed in the same manner asdescribed above using a phenol-based antioxidant such asSumilizer-GA-80, Sumilizer-BP-101, Sumilizer-BP-76 (all available fromSumitomo Kagaku Kogyo Co., Ltd.), 3,5-di-tert-butyl-4-hydroxy toluene(BHT), a phosphorus-based antioxidant such as Sumilizer-P-16 andAdecastab PEP-24G, sulfur-based antioxidant such as Sumilizer-TPM andSumilizer-TP-D (all available from Sumitomo Kagaku Kogyo Co., Ltd.), andan HALS-type antioxidant such as Sanol LS-770 (Sankyo Co., Ltd.) inplace of the ester-type antioxidant. Even when any of these antioxidantsis used, it is possible to provide a good pattern as in the case ofExample 2.

[0368] Incidentally, when annealing is performed in air without addingan antioxidant, the size of holes and dispersion of intervals betweenholes in the formed pattern are increased. It is confirmed from theseresults that the addition of an antioxidant to the diblock copolymer iseffective.

Example 25

[0369] A phenol-based antioxidant such as Sumilizer-GA-80,Sumilizer-BP-101 and Sumilizer-BP-76 (all available from Sumitomo KagakuKogyo Co., Ltd.), BHT, the aforementioned ester type antioxidant, aphosphorus-based antioxidant such as Sumilizer-P-16 and AdecastabPEP-24G, a sulfur-based antioxidant such as Sumilizer-TPM andSumilizer-TP-D (all available from Sumitomo Kagaku Kogyo Co., Ltd.), andan HALS-type antioxidant such as Sanol LS-770 (Sankyo Co., Ltd.) areprovided.

[0370] A pattern transfer step and patterning of SiO₂ film are performedin the same manner as described in Example 5 except that 0.1 wt % of anantioxidant is added to polysilane constituting a pattern transfer filmand that annealing for forming a microphase separation is performed inair. As a result, even when any of these antioxidants is used, it ispossible to increase the depth of the holes by about 30% as comparedwith that obtained in Example 5.

Example 26

[0371] A phenol-based antioxidant such as Sumilizer-GA-80,Sumilizer-BP-101 and Sumilizer-BP-76 (all available from Sumitomo KagakuKogyo Co., Ltd.), BHT, the aforementioned ester-type antioxidant, aphosphorus-based antioxidant such as Sumilizer-P-16 and AdecastabPEP-24G, a sulfur-based antioxidant such as Sumilizer-TPM andSumilizer-TP-D (all from Sumitomo Kagaku Kogyo Co., Ltd.), and anHALS-type antioxidant such as Sanol LS-770 (Sankyo Co., Ltd.) areprovided.

[0372] Patterning is performed in the same manner as described inExample 13 except that 0.1 wt % of an antioxidant is added to thediblock copolymer and that annealing for forming microphase separationis performed in air. As a result, even when any of these antioxidants isused, it is possible to increase the depth of the holes formed in theSiO substrate by about 20% as compared with that obtained in Example 13.

[0373] Incidentally, when annealing is performed in air without addingan antioxidant, the size of holes and intervals between holes in theformed pattern are increased, and at the same time, the depth of holesis decreased by about 20%. It is confirmed from these results thataddition of an antioxidant to the diblock copolymer is effective.

Example 27

[0374] An example of manufacturing a field emission display (FED) asshown in FIG. 9 will be described. The cathode conductor 102 consistingof a thin film made of a metal such as niobium (Nb), molybdenum (Mo) oraluminum (Al) is formed on the insulative substrate 101 such as glass. Aportion of the cathode conductor 102 is etched by means ofphotolithography to form a rectangular cut-out portion having a sidelength of about 40 to 100 μm. The resistance layer 103 having athickness of 0.5 to 2.0 μm is formed to cover the cathode conductor 102by sputtering or CVD. As for the material for the resistance layer 103,In₂O₃, Fe₂O₃, ZnO or NiCr alloy or silicon doped with impurities can beemployed. The resistivity of the resistance layer 103 should preferablybe in the range of about 1×10 to 1×10⁶ Ωcm.

[0375] The resistance layer 103 is patterned by wet etching with analkaline solution such as ammonia or reactive ion etching (RIE) with afluorine-based gas, thereby forming a plurality of terminals 103A. Then,the insulating layer 104 consisting of silicon dioxide and having athickness of about 1.0 μm is formed by sputtering or CVD to cover thecathode conductor 102 and the resistance layer 103. Further, the gateconductor 105 made of Nb or Mo having a thickness of 0.4 μm is formed bysputtering on the insulating layer 104.

[0376] Then, a resist (OFPR 800, 100pc, Tokyo Ohka Co., Ltd.) ispatterned to protect intersecting portions between gate wires andemitter wires. Subsequently, according to Example 6, a solution of thediblock copolymer (5) and polystyrene homopolymer is applied to the gateconductor 105 by spin coating and then dried, followed by annealing,thereby forming a film having micro polymer phases. RIE with CF₄ gas isperformed to the film having micro polymer phases, thus the PMMA in thefilm having micro polymer phases is selectively etched, and further thegate conductor 105 is etched with using the pattern of remaining PS asmask, thereby transferring the pattern to the gate conductor 105.Thereafter, ashing is performed with an O₂ asher, thereby removing theremaining organic substances. In such a manner, many openings 106 havinga diameter of about 840 nm are formed in the gate conductor 105. Wetetching with a buffered hydrofluoric acid (BHF) or RIE with a gas suchas CHF₃ is performed to remove the insulating layer 104 in the openings106 until the resistance layer 103 is exposed to the outside.

[0377] Then, aluminum is obliquely deposited by electron beam (EB)evaporation to form a peeling layer. Molybdenum is normally deposited onthe peeling layer in the perpendicular direction by EB evaporation,thereby depositing molybdenum in a conical configuration inside theopenings 106 to form the emitters 107. Thereafter, the peeling layer isremoved with a peeling solution such as phosphoric acid, therebymanufacturing an FED device as shown in FIG. 9.

Example 28

[0378] An example of manufacturing an FED device as shown in FIG. 10will be described. The Pyrex glass substrate 201 having a width acrosscorner of 14 inches and a thickness of 5 mm is cleaned, and then thesurface thereof is roughened by plasma treatment. The emitter wires 202having a width of 350 μm are formed on the glass substrate 201 parallelto the long side of the glass substrate 201 with a pitch of 450 μm. Onthis occasion, the regions on the substrate 201 having a width of 2inches measured from each side parallel to the direction of the emitterwires 202 are made margins, respectively, for which patterning isperformed so that the emitter wires 202 are not formed in these regions.Specifically, patterning is performed in such a manner that a PVA filmis applied to the substrate, which is exposed to an ultraviolet raythrough a mask (photopolymerizedj, followed by being developed, so as toleave the PVA film in the regions between the emitter wires 202. Thepatterning precision at that time is 15 μm. A 50-nm thick Ni film isdeposited by electroless plating, and then the PVA film and the Ni filmthereon are lifted-off. A 1-μm thick Au film is deposited byelectroplating using the remaining Ni film as an electrode.

[0379] The SiO₂ film 203 having a thickness of 1 μm as an insulatingfilm is deposited by means of an LPD method. Even though a large numberof particle defects are included in SiO₂ film 203, the density thereofis about 1,000/cm², which is in a level that brings about no problem inpractical viewpoint. Although the film formed on the Au layer isslightly darkened, the film has a breakdown voltage of 100V per 1 μm,which is in a level that brings about no problem in practical viewpoint.The SiO₂ film 203 covers step portions of Au—Ni wire conformally, thusthere are no exposed portions of Au. A 30-nm thick Pd film is depositedon the SiO₂ film 203 by electroless plating, and then a 200-nm thick Irfilm is deposited by electroplating to form a gate film. Then, the gatefilm is patterned in the direction parallel to the shorter side of thesubstrate, thereby forming the gate wires 204 having a width of 110 μmwith a pitch of 150 μm. On this occasion, the regions on the substrate201 having a width of 2 inches measured from each side parallel to thedirection of the gate wires 204 are made margins, respectively, forwhich patterning is performed so that the gate wires 204 are not formedin these regions. Specifically, patterning is performed in such a manneras described above that a PVA film is applied to the substrate, which isexposed to an ultraviolet ray through a mask (photopolymerized),followed by being developed, so as to leave the PVA film on the gatewires 202 and remove the remaining exposed regions of the PVA film. Thepatterning precision at that time is also 15 μm.

[0380] Next, patterning is performed to remove a part of the gate wires204 and SiO₂ film 203 until the emitter wire 202 is exposed to theoutside, thereby forming the openings 205 in an approximately circularform. There are two reasons for separately performing the patterning ofthe gate wires 204 and the patterning of the SiO₂ film 203. One of thereasons is that, since the diameter of the openings 205 is about 1 μm,it is required to employ a patterning method ensuring optical resolutionof 1 μm or so. The other reason is that, since the openings 205 are notnecessarily arrayed regularly, it is only required that the openings 205having approximately uniform diameter are present in almost equalnumbers for respective pixels.

[0381] Specifically, patterning for the openings 205 is performed asfollows. A diblock copolymer (polystyrene: Mw=150,700, poly(t-butylacrylate): Mw=1033,000, Mw/Mn=1.30) and polystyrene homopolymer(Mw=45,000, Mw/Mn=1.07) are blended together at a weight ratio of 21:79,and then the blend is dissolved in cyclohexane with 5 wt % of solidmatters, to which 1% of naphthylimide triflate, based on the solidmatters, is added as a photo-acid generator, followed by filtering. Thesolution is applied to the gate wires 204 by spin coating, followed bydrying at 110° C., thereby forming a polymer film having a thickness of970 nm. Excluding the intersecting portions between the gate wires 204and the emitter wires 202, only the regions where the openings 205 areto be formed are exposed to g-line, thereby generating acid from thephoto-acid generator. The sample is placed in an oven and subjected toannealing in a nitrogen atmosphere at 150° C. for one hour, therebyforming a film having micro polymer phases, and, at the same time,decomposing exposed portions of poly(t-butyl acrylate) with acid toconvert into polyacrylic acid. Note that, since reflow of the polymeroccurs during annealing, the thickness of the polymer film on the gatewires 204 is decreased to 1 μm. The substrate is entirely immersed in analkaline solution for 3 minutes to remove the “island” portions of theacrylic acid, followed by rinsing with pure water, thus the gate wires204 are exposed to the outside. RIE is performed to etch the gate wires204 and further to etch the SiO₂ film 203 under the gate wires 204, thusthe emitter wires 202 are exposed to the outside.

[0382] Next, the resistance layer 206 is deposited inside the openings205 by electrophoresis. The operation is performed for separated regionseach including 100 lines of emitter wires, respectively. As a materialfor the resistance layer 206, employed is a mixture of polyimide fineparticles having particle size of 100 nm (PI Technique Research Co.,Ltd.) and carbon fine particles containing fullerene having a particlesize of 10 nm at a weight ratio of 1000:1. The mixture is dispersed by0.4 wt % in a dispersion solvent (Isoper L, Exxon Chemical Co., Ltd.).On the other hand, zirconium naphthenate (Dai Nippon Ink Kagaku KogyoCo., Ltd.) as a metal salt is added by 10 wt % to the mixture ofpolyimide and carbon fine particles. The substrate 201 is immersed inthe dispersion solution and an counter electrode is disposed at a spaceof 100 μm away from the substrate 201, and the emitter wires 202 aregrounded, under which setting a voltage of +100V is applied to thecounter electrode while applying an ultrasonic wave. Immediately afterthe application of the voltage, a current of several mA begins to flow,but the current is exponentially attenuated, which comes to be notobserved two minutes later. At this moment, the resistance materialdispersed in the dispersion solvent is all deposited on the substrate201. Subsequently, the counter substrate is grounded and a voltage of+50V is applied to the gate wire 204, thereby migrating the fineparticles adhered on the gate wire 204 in the solvent so as to beremoved. Further, annealing is performed in a nitrogen gas atmosphere at300° C. to fix the resistance layer 206 to the emitter wires 202.

[0383] Then, a fine particle-emitter layer 207 is deposited on theresistance layer 206 by electrophoresis in the same manner as describedabove. As a material for the fine particle-emitter layer 207, cubicboron nitride fine particles having a particle size of 100 nm (tradename SBN-B, Showa Denko Co., Ltd.) are provided. The BN fine particlesare treated with hydrofluoric acid, followed by hydrogen plasma treatingat 450° C. The BN fine particles are dispersed by 0.2 wt % in the samesolvent as employed in the deposition of the resistance layer. Further,zirconium naphthenate is added by 10 wt % to the BN fine particles.After the BN fine particles are deposited in the same manner asdescribed above, the BN fine particles adhered on the gate wires 204 areremoved. Further, annealing in a hydrogen atmosphere at 350° C., therebyfixing the fine particle-emitter layer 207 to the resistance layer 206.

[0384] To the resultant electron-emitting element array, a faceplate 211provided with an anode layer 212 made of ITO and a phosphor layer 213 ismounted with interposing spacers 208 having a height of 4 mm, whichproduct is placed in a vacuum chamber. The pressure inside the vacuumchamber is reduced to 10⁻⁶ Torr by means of a turbo-molecular pump. Theanode potential is set to 3500V. The potentials of non-selected emitterwires 202 and gate wires 204 are both set to 0V. The potentials of aselected emitter wire 202 and a gate wire 204 are biased to −15V and+15V, respectively. As a result, electron emission is caused, and hencea bright spot is observed on the fluorescence layer 213. Several pixelsare selected from the entire displaying region of the display to measurefor brightness under the same conditions. As a result, dispersion of thebrightness is found to be within 3%.

Example 29

[0385] First, for the purpose of employing a porous film manufacturedfrom a block copolymer as a separator of a lithium ion secondarybattery, a preliminary experiment is performed as follows.

[0386] A diblock copolymer comprising a polyvinylidene fluoride chainand a polymethyl methacrylate chain (weight average molecular weightMw=79,000, Mw/Mn=2.2, and weight fraction of polyvinylidenefluoride=66%) is dissolved in a solvent, to which silica (Tokuseal P,Tokuyama Soda Co., Ltd.) is added by 3 wt % based on the diblockcopolymer. The resultant solution is cast to provide a cast film of thediblock copolymer. The film is heat-treated under a nitrogen flow at130° C. for hours to form a structure having micro polymer phasestherein. When the structure having micro polymer phases is observed withTEM, a bicontinuous structure having a pore size of 40 nm or so isformed. The cast film is irradiated with an electron beam under theconditions of 2 MV in accelerating voltage and 10 kGy in exposure dose,thereby decomposing the polymethyl methacrylate phase, and, at the sametime, cross-linking the polyvinylidene fluoride phase to cause gelation.The film is rinsed with ethyl acetate to remove the polymethacrylatephase. TEM observation shows that a porous film is formed havingcontinuous pores retaining the bicontinuous structure.

[0387] LiClO₄ anhydride is dissolved in a mixed solvent of propylenecarbonate and dimethyl carbonate (1:1) to prepare a 1M concentration ofelectrolyte solution. The porous film having a thickness of about 50 μmobtained as above is impregnated with the electrolyte solution, and thefilm is punched out into a disk having a diameter of 0.5 cm. Theelectrolyte-impregnated porous film is sandwiched between a pair ofplatinum electrodes to constitute a cell, which is measured for ACimpedance using an impedance gain phase analyzer 1260 (SchlumbergerInstruments Co., Ltd.) at room temperature and at a frequency of 30 MHzto 0.05 Hz. As a result, the film exhibits good ion conductivity of 4mScm⁻¹ at 25° C. In addition, the porous film holds the electrolytesolution well, and hence, no liquid leakage occurs.

[0388] Next, a lithium ion secondary battery is manufactured as follows.

[0389] As an active material for a positive electrode, LiCoO₂ isemployed. The LiCoO₂ is heated under an argon atmosphere at 300° C. for3 hours so as to be dried. Thereafter, LiCoO₂, conductive carbon blackand the above diblock copolymer are mixed together at a ratio of85:10:5, to which mixture a small quantity of DMF is added, and thenkneaded. The kneaded product is uniformly applied to an aluminum meshhaving a thickness of 20 μm and a size of 4 cm×4.5 cm and dried tomanufacture a positive electrode having a thickness of about 50 μm. Theresultant positive electrode has LiCoO₂ weight per unit area of 17mg/cm². The active material for positive electrode shows a capacity of150 mAh/g.

[0390] As an active material for a negative electrode, hard carbon(non-graphitizing carbon) that is obtained by sintering furfuryl alcoholat 1,100° C. is employed. The hard carbon is heated under an argonatmosphere at 600° C. for 3 hours so as to be dried. The hard carbon,conductive carbon black and the above diblock copolymer are mixedtogether at a weight ratio of 85:10:5, to which mixture a small quantityof DMF is added, and then kneaded. The kneaded product is uniformlyapplied to a copper mesh having a thickness of 20 μm and a size of 4cm×4.5 cm and dried to manufacture a negative electrode having athickness of about 50 μm. The resultant positive electrode has hardcarbon weight per unit area of 7 mg/cm². The active material fornegative electrode shows a capacity of 150 mAh/g.

[0391] The aforementioned diblock copolymer is dissolved in a solvent,to which silica (Tokuseal P, Tokuyama Soda Co., Ltd.) is added 3 wt %based on the diblock copolymer. The solution is cast to form a cast filmof the diblock copolymer. The positive electrode, the negative electrodeand the cast film are respectively heat-treated under a nitrogen flow at130° C. for 5 hours, and then they are irradiated with electron beamunder the conditions of 2 MV in accelerating voltage and 10 kGy inexposure dose. The positive electrode, the cast film and the negativeelectrode are laminated in the order, followed by pressing with a hotpress, to manufacture a laminate. The laminate is rinsed with ethylacetate to remove the polymethacrylate phase in the diblock polymer. Thelaminate is heated under vacuum at 70° C. for 20 hours so as to bedried, thereby manufacturing a cell structure. LiPF₆ anhydride isdissolved in a mixed solvent of propylene carbonate and dimethylcarbonate (1:1) to prepare a 1M concentration of electrolyte solution.The cell structure is immersed in the electrolyte solution to beimpregnated with the electrolyte solution. The resultant cell structureis wrapped with waterproof and airtight aluminum laminate film andsealed under an argon flow. External electrode terminals are connectedthe negative and positive electrodes, respectively, therebymanufacturing a lithium ion secondary battery.

[0392] The resultant lithium ion secondary battery is charged with aconstant current of 50 μA/cm², and, after the battery voltage reaches4.2V, charged with a constant voltage. The charging time is defined asthe time at which excessive capacity of 30% is charged relative to thecapacity of 300 mAh/g of the active material for the negative electrode.After completion charging, the battery is allowed to stand for 30minutes, and then the battery is discharged with a constant current of50 PA/cm² until the battery voltage decreases to 2.5V. After completionof discharging, the battery is allowed to stand for 30-minutes. Theabove procedures are defined as one cycle, and the charge-and-dischargecycles are repeated to examine the battery capacity per gram of theactive material (hard carbon) for the negative electrode (i.e., negativeelectrode-reduced capacity: mAh/g) and the charge-and-dischargeefficiency (%) (a ratio of discharge capacity to charge capacity), foreach cycle.

[0393] Even when the charge-and-discharge cycle test is repeated up to500 cycles, any substantial change is not recognized in acharge-and-discharge curve and the battery capable is maintained at 80%or more, showing excellent in charge-and-discharge characteristics.Further, no internal short-circuit occurs. A lithium ion secondarybattery manufactured in the same manner as described above except thatthe positive and negative electrodes and cast film are laminated,followed by hot-pressing, which laminate is irradiated with an electronbeam, also shows excellent characteristics similar to those describedabove.

Example 30

[0394] A diblock copolymer comprising a polyvinylidene fluoride chainand a polymethyl methacrylate chain (weight average molecular weightMw=79,000, Mw/Mn=2.2, and weight fraction of polyvinylidenefluoride=66%) is dissolved in a solvent to prepare a solution. Thesolution is applied to a fiber of polymethyl methacrylate by dipcoating, followed by being air-dried at 70° C., and further the fiber isheated and dried under a nitrogen flow at 135° C. for 10 hours, and thusa film is formed on the surface of the polymethyl methacrylate fiber.The surface of the fiber is irradiated with an electron beam under theconditions of 2 MV in accelerating voltage and 10 kGy in exposure dose,thereby decomposing the polymethacrylate phase, and, at the same time,cross-linking the polyvinylidene fluoride phase to cause gelation. Thefiber is rinsed with ethyl acetate to remove the polymethacrylate phase,thereby providing a porous hollow fiber. The resultant porous hollowfiber has an inner diameter of 500 μm and an outer diameter of 530 μm,and the side wall thereof has a porous structure retaining a Gyroid typephase-separated structure having a pore size of 40 nm.

[0395] A filter module having an effective length of 25 cm ismanufactured using a hundred hollow fibers obtained, and the module isused for filtration of a solution of silica sol having an averageparticle size of 100 nm. No silica sol is observed in the filtrate.

Example 31

[0396] Pellets of a diblock copolymer comprising a polyacrylic acidchain and a polymethyl methacrylate chain (weight average molecularweight Mw=82,000, Mw/Mn=1.3, and weight fraction of polyacrylicacid=26%) are prepared with using an extruder. The pellets are fed intoa uniaxial extruder and extrusion-molded into a fiber having a diameterof 50 μm. A plain weave fabric is made using the fiber, and then thefabric is heat-treated under a nitrogen flow at 135° C. for 10 hours.Thereafter, the fabric is irradiated with an electron beam under theconditions of 2 MV in accelerating voltage and 10 kGy in exposure dose,thereby decomposing the PMMA phase. The fabric is rinsed with a mixedsolvent of MIBK and isopropyl alcohol (volume ratio: 3.7) to remove thePMMA phase. Observation of the resultant fabric with SEM shows that thefabric is formed of an aggregate consisting of a bundle of ultrafinefibers made of polyacrylic acid having a diameter of about 26 nm. It isassumed from the result that the annealed fiber is formed into acylindrical structure.

Example 32

[0397] A fabric is manufactured in the same manner as in Example 32except that a diblock copolymer comprising a polyacrylic acid chain anda polymethyl methacrylate chain (weight average molecular weightMw=104,000, Mw/Mn=1.3, and weight fraction of polyacrylic acid=55%) isemployed. Observation of the fabric with SEM shows that the fabric isformed of an aggregate consisting of a bundle of fibers in a form ofthin piece made of polyacrylic acid having a thickness of 67 nm. It isassumed from the result that the annealed fiber is formed into a lamellastructure.

Example 33

[0398] A fabric is manufactured in the same manner as in Example 32except that a diblock copolymer comprising a polyacrylic acid chain anda polymethyl methacrylate chain (weight average molecular weightMw=42,000, Mw/Mn=1.3, and weight fraction of polyacrylic acid=65%) isemployed. Observation of the fabric with TEM shows that the fabric isformed of porous fibers made of polyacrylic acid including continuouspores having an average pore size of 16 nm. It is assumed from theresult that the annealed fiber is formed into a bicontinuous structure.

Example 34

[0399] A 2-wt % of diblock copolymer (molecular weight:polystyrene=65,000; polymethyl methacrylate=13,200; Mw/Mn=1.04) isdissolved in propyleneglycol monoethyl ether acetate (PGMEA) to preparea solution, followed by filtering, and then the solution is applied to aSiO substrate having a diameter of 3 inches by spin coating at a rate of2,500 rpm. The substrate is heated at 120° C. for 90 seconds toevaporate the solvent. Then the substrate is placed in an oven andsubjected to annealing in a nitrogen atmosphere at 210° C. for 10minutes, subsequently at 135° C. for 10 hours. As a result, formed is afilm having micro polymer phases of a sea-island structure includingislands having a diameter of 17 nm.

[0400] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave. Under theconditions, the PMMA is selectively etched, and further the underlayeris etched with the remaining PS pattern being used as a mask. A 15-nmthick CoPtCr film is deposited by ordinary sputtering on the sample thathas been subjected to etching. The sample on which the CoPtCr film isdeposited is immersed in a cellosolve-based solvent and subjected toultrasonic cleaning, and thus the remaining polystyrene and the CoPtCrfilm thereon are lifted off. The surface of the sample after lift-offprocess is observed with a scanning electron microscope. As a result,observed is a structure that CoPtCr magnetic particles having a size ofabout 17 nm are present in the glass substrate matrix.

[0401] In order to use the sample as a high-density magnetic recordingmedium, carbon having a thickness of 10 nm is deposited as a protectivefilm on the substrate by sputtering, from which anomalous projectionsare removed by tape vanishing, and then a lubricant is applied theretoin a wet process. Measurement for the magnetic characteristics of thesample shows perpendicular magnetic anisotropy with coercivity of 2 kOe.

[0402] Alternatively, a magnetic recording medium is manufactured in thesame manner as described above except that patterning of the diblockcopolymer is preformed according to the method in Example 2. As aresult, the resultant magnetic recording medium has almost the samecharacteristics as above.

[0403] Further, a magnetic recording medium is manufactured in the samemanner as described above except that patterning of the diblockcopolymer is preformed according to the method in Example 4. Since thedepth of holes formed by using the method is as deep as 30 nm, theresultant magnetic recording medium has higher coercivity than that ofabove magnetic recording medium.

Example 35

[0404] First, a diblock copolymer of polystyrene (molecular weight:6,300) and polymethyl methacrylate (molecular weight: 13,000) with Mw/Mnof 1.4 is dissolved in propyleneglycol monoethyl ether acetate (PGMEA)to prepare a solution. The solution is applied in a thickness of about10 nm to a glass substrate having a diameter of 2.5 inches by spincoating. The coated substrate is placed in a thermostat and subjected toannealing at 150° C. for 24 hours, and further at 120° C. for 2 hours,and the returned to room temperature. The surface of the glass substratesample after annealing is observed with a scanning electron microscope.As a result, it is confirmed that a structure in which spherical islandshaving an average diameter of 17 nm and the sea surrounding the islandsare phase-separated is formed.

[0405] Reactive ion etching (RIE) treatment with CF₄ is performed to thesample. As a result, only the island portions are selectively etched.Measurement for thickness of the film shows that the selectivity betweenthe island and sea to RIE is sea: island=1:4.

[0406] A 15-nm thick CoPtCr film is deposited by ordinary sputtering onthe sample that has been subjected to etching. The sample on which theCoPtCr film is deposited is immersed in a cellosolve-based solvent andsubjected to ultrasonic cleaning, and thus the remaining polystyrene andthe CoPtCr film thereon are lifted off. The surface of the sample afterlift-off process is observed with a scanning electron microscope. As aresult, observed is a structure that CoPtCr magnetic particles having asize of about 15 nm are present in the glass substrate matrix.

[0407] In order to use the sample as a high-density magnetic recordingmedium, carbon having a thickness of 10 nm is deposited as a protectivefilm on the substrate by sputtering, from which anomalous projectionsare removed by tape vanishing, and then a lubricant is applied theretoin a wet process. Measurement for the magnetic characteristics of thesample shows perpendicular magnetic anisotropy with coercivity of 2 kOe.

Example 36

[0408] An aluminum layer having a thickness of 500 nm is formed on asilicon wafer, and then the aluminum layer is patterned using a resistfor semiconductor (EOBR-800), thereby forming a pair of electrodesspaced apart from each other by 5 μm. A SiO₂ film is formed on thewafer, and the surface thereof is flattened by CMP, thereby exposing theelectrode portions to the outside. An aluminum layer having a thicknessof 20 nm is deposited on the wafer, and then a SiO layer having athickness of 5 nm is deposited on the aluminum layer. Patterning forforming electrodes is again performed using the resist for semiconductor(EOBR-800), and then, RIE is slightly performed so as to expose theelectrode portions to the outside.

[0409] A diblock copolymer (molecular weight: polystyrene=146,700;polymethyl methacrylate=70,700; Mw/Mn=1.11) is dissolved in PGMEA toprepare a 2 wt % solution, which is applied to the wafer by spin coatingat a rate of 3,000 rpm, and then the wafer is placed on a hot plateheated at 120° C. to form a diblock polymer thin film having a thicknessof 45 nm.

[0410] The thin film is annealed in a nitrogen atmosphere at 230° C., 40hours, while applying a voltage of 10V between the electrodes. Duringthe operation, the diblock copolymer of polystyrene and polymethylmethacrylate causes microphase separation, resulting in a structure thatcylinder phases are oriented perpendicular to the electrodes. The waferis cooled to 80° C. over two hours, and further naturally cooled to roomtemperature.

[0411] The wafer is then subjected to reactive ion etching with CF₄under the conditions of 0.01 Torr, 30 sccm, and 150 W of progressivewave for 180 seconds. As a result, the PMMA phases are selectivelyetched, and further underlying aluminum is also etched. As a result, anelectrode in a comb shape having intervals of about 50 nm is formedbetween electrodes spaced apart from each other by 5 μm.

Example 37

[0412] Aluminum is deposited on a silicon wafer to form a thin filmhaving a thickness of 10 nm. A 10-wt % solution of a diblock copolymer(molecular weight: polystyrene=322,400; polymethyl methacrylate=142,000;Mw/Mn=1.11) in toluene is applied to the wafer by spin coating at a rateof 3,000 rpm, and then the wafer is placed on a hot plate heated at 120°C. to form a diblock polymer thin film having a thickness of 500 nm. Thethin film is dried in vacuum at 60° C. over 14 days. Further, aluminumis deposited on the thin film of the diblock copolymer to form a thinfilm having a thickness of 10 nm.

[0413] The thin film is annealed in a nitrogen atmosphere at 210° C. for40 hours, while applying a voltage of 1V between a pair of aluminumlayers. During the operation, the diblock copolymer of polystyrene andpolymethyl methacrylate causes microphase separation, resulting in astructure that cylinder phases are oriented perpendicular to theelectrodes. The wafer is cooled to 80° C. over two hours, and furthernaturally cooled to room temperature.

[0414] The wafer is then subjected to reactive ion etching with CF₄under the conditions of 0.01 Torr, 30 sccm, and 150 W of progressivewave for 600 seconds. As a result, the PMMA phases are selectivelyetched, and further underlying aluminum and the substrate are alsoetched. Ashing with oxygen is performed to remove the remaining polymer.As a result, trenches having a diameter of 100 nm at maximum and a depthof 1 μm can be provided in the substrate.

Example 38

[0415] A Pyrex glass substrate is cleaned, and then the surface thereofis roughened by plasma treatment. Gold is deposited on the glasssubstrate to form a thin film having a thickness of 100 nm. A 10-wt %solution of a diblock copolymer comprising a polystyrene chain and apolymethyl methacrylate chain (weight average molecular weightMw=37,000, Mw/Mn=1.3, and weight fraction of polymethylmethacrylate=26%) in toluene is applied to the substrate by spincoating, and then the substrate is placed on a hot plate heated to dryat 120° C. to form a diblock polymer thin film having a thickness of 500nm. The thin film is dried in vacuum at 60° C. over 14 days. Further,aluminum is deposited on the thin film of the diblock copolymer to forma thin film having a thickness of 50 nm.

[0416] The thin film is annealed in a nitrogen atmosphere at 210° C. for40 hours, while applying a voltage of 1V between the gold film and thealuminum film. During the operation, the diblock copolymer ofpolystyrene and polymethyl methacrylate causes microphase separation,resulting in a structure that cylinder phases are oriented perpendicularto the electrodes. The substrate is cooled to 80° C. over two hours, andfurther naturally cooled to room temperature.

[0417] Then, the aluminum deposited film formed on the surface isremoved by immersing the substrate in an aqueous solution ofhydrochloric acid, and then the substrate is irradiated with an electronbeam. After electron beam irradiation, the cast film is rinsed with amixed solution of MIBK and IPA in 3:7 by volume ratio, thereby makingthe polymer film porous. Observation of the porous polymer film with anelectron microscope shows that holes, which reach the gold film, havinga diameter of 10 nm are formed perpendicular to the substrate. Theporous film is subjected to potentiostatic electrolysis in a goldplating bath to deposit gold in the through-holes. When the porouspolymer layer is removed by ashing with oxygen after electroforming,provided is a structure in which many gold fibers having a diameter ofabout 8 nm are arranged on the gold film with perpendicularly orientedto the substrate like a pinholder. Likewise, when iridium is subjectedto electroforming, it is possible to provide a pinholder structuresimilar to that in the case of gold.

[0418] Then, the field emission ability of the pinholder structure isexamined. By making use of the gold film bearing the pinholder structureof iridium having a diameter of 8 nm as a cathode electrode, and bymaking use of an ITO substrate on which red-emitting europium-dopedAl₂O₃ phosphor as a counter anode electrode, a cell having a spacebetween electrodes of 30 μm is manufactured. The cell is actuated at avoltage of 300V in vacuum (1×10⁻⁶ Torr). As a result, it is observed redemission due to effective field emission, which shows that the pinholderstructure is capable of operating as emitters of a cold emissiondisplay.

[0419] Further, an FED panel is manufactured by making use of theemitter in the pinholder structure. In this case, the FED panel ismanufactured by the same procedures as described in Example 27 exceptthat, instead of forming a Spindt type emitter on an insulating layer byEB evaporation, the pinholder structure of iridium is formed asdescribed above. To the resultant electron emission element array, aface plate provided with an anode layer made of ITO and with a phosphorlayer is mounted through spacers having a height of 4 mm, in the samemanner as described in Example 28, and then the circumferential portionsof the panel is sealed leaving a discharge port for evacuation. Thepressure inside the element panel is reduced with a turbo-molecular pumpto 10⁻⁶ Torr, and then the discharge port is completely sealed tomanufacture the FED panel. In order to operate the FED panel, the anodepotential is set to 3500V, the potentials of non-selected emitter wiresand gate wires are both set to 0V, and the potentials of selectedemitter wire and gate wire are biased to −15V and +15V, respectively. Asa result, electron emission is caused, and hence a bright spot isobserved on the fluorescence layer. Several pixels are selected from theentire displaying region of the display to measure for brightness underthe same conditions. As a result, dispersion of the brightness is foundto be within 3%.

Example 39

[0420] Gold is deposited on a copper foil to form a thin film having athickness of 100 nm. A 10-wt % solution of a diblock copolymercomprising a polystyrene chain and a polymethyl methacrylate chain(weight-average molecular weight Mw=370,000, Mw/Mn=1.2, and weightfraction of polymethyl methacrylate chain=26%) in toluene is cast andair-dried and further drying is performed in vacuum at 60° C. for 8hours to form a diblock polymer film having a thickness of 30 nm.Aluminum is deposited on the cast film to form a film having a thicknessof 50 nm.

[0421] Annealing is performed in a nitrogen atmosphere at 210° C. for 40hours, while applying a voltage of 60V between the gold film and thealuminum film. During the operation, microphase separation of thediblock copolymer of the polystyrene and polymethyl methacrylate iscaused, and cylinder phases of polymethyl methacrylate are orientedperpendicular to the electrodes. The sample is cooled to 80° C. over twohours, and then naturally cooled to room temperature.

[0422] Thereafter, the aluminum deposition film formed on the surface isremoved by immersing the sample in an aqueous solution of hydrochloricacid, and then the sample is irradiated with an electron beam. After theelectron beam irradiation, the cast film is rinsed in a 3:7 mixedsolution of MIBK and IPA to make the polymer film porous. When theporous polymer film is observed with an electron microscope, it is foundthat holes having a diameter of 120 nm, which reach the gold film, areformed perpendicular to the substrate. The porous film is subjected topotentiostatic electrolysis in a nitrogen-purged Bi³⁺/HTeO²⁺ bath usinga platinum mesh as a counter electrode, thereby depositing bismuthtelluride in the through-holes. When the porous polymer layer is removedafter the electroforming, it is possible to obtain a structure in whichmany bismuth telluride fibers having a diameter similar to that of thecylinder and oriented perpendicular to the substrate are formed on thegold film like a pinholder. The bismuth telluride fiber can be employedfor a high-efficiency thermoelectric conversion element.

Example 40

[0423] A solution of a diblock copolymer comprising a polystyrene chainand a polymethyl methacrylate chain (weight-average molecular weightMw=82,000, Mw/Mn=1.3, and weight fraction of polystyrene chain=26%) isapplied to an aluminum wire by dip coating. After application, the wireis air-dried. After drying, aluminum is deposited on the surface ofcoating by a thickness of 100 nm. After deposition, annealing isperformed in a nitrogen atmosphere at 200° C. for 40 hours, whileapplying a voltage of 30V between the aluminum wire and the aluminumdeposited film. During the annealing, microphase separation of thediblock copolymer of the polystyrene and polymethyl methacrylate iscaused, and cylinder phases are oriented perpendicular to theelectrodes. The wire is cooled to 80° C. over two hours, and thennaturally cooled to room temperature. After the heat treatment, the wireis immersed in an aqueous solution of hydrochloric acid to remove thealuminum deposited film formed on the surface of the wire. After thesurface aluminum deposited film is removed, the wire is irradiated withan electron beam at a dose of 150 KGr. After the electron beamirradiation, the cast film is rinsed in the mixed solution of MIBK andIPA in the ratio of 3:7 by volume to make the polymer film porous. Thewire is immersed in an aqueous solution of hydrochloric acid to dissolveand remove the aluminum wire forming the core, and thus a hollow fiberfilter is provided. The resultant hollow fiber has an inner diameter of500 μm and an outer diameter of 530 μm, whose wall surface represents aporous structure to which a cylinder type phase-separated structurehaving a pore size of about 27 nm is transferred. The cylindrical finepores are formed into through-holes oriented perpendicular to the wallsurface, which shows a suitable form for a filter.

[0424] When a minimodule (effective length: 25 cm) using 100 hollowfiber filters is manufactured, the module works well as a filterapparatus.

Example 41

[0425] A diblock copolymer comprising a polyacrylic acid chain and apolymethyl methacrylate chain (weight-average molecular weightMw=82,000, Mw/Mn=1.3, and weight fraction of polyacrylic acid chain=26%)is palletized with an extruder, and then the pellets are extrudedthrough a T-die to form a film having a thickness of about 100 μm. Thefilm is heat-treated under a nitrogen gas flow at 135° C. for 10 hours.After the heat treatment, the film is irradiated with an electron beamat the dose of 150 kGy. After the electron beam irradiation, the film isrinsed in the mixed solution of MIBK and IPA in the ratio of 3:7 byvolume. SEM and TEM observation shows that formed is a flat materiallike a non-woven fabric in which fiber bundles of ultra fine fiberhaving a thickness of 26 nm are entangled. The flat material showsexcellent flexibility and can also be used well as a high-precisionfilter.

Example 42

[0426] A diblock copolymer of 1,2-polybutadiene and polymethylmethacrylate (Mw=281,000, weight fraction of 1,2-polybutadiene=32%,Mw/Mn=1.05) is mixed with a 2-wt % of3,3′,4,4′-tetra(t-butylperoxycarbonyl) benzophenone, and a cyclohexanonesolution thereof is prepared. The solution is applied to a glass plateusing an applicator to form a sheet having a thickness of 20 μm. Thesheet is subjected to heat treatment under a nitrogen gas flow at 135°C. for two hours. The sheet is irradiated with an electron beam underthe conditions of 2 MV in accelerating voltage and 200 kGy in exposuredose. The sheet is rinsed with ethyl lactate for 24 hours, and thenrinsed with methanol for one hour to provide a porous sheet. Theresultant porous sheet has a porous structure to which transferred is abicontinuous phase-separated structure consisting of polybutadienecylinder phases having a diameter of about 50 nm and highly branched ina three-dimensional network configuration.

[0427] The resultant porous sheet is subjected to repeating processescomprising steps of being impregnated with a poly(2-bromoethyl)silsesquioxane, being irradiated with an ultraviolet ray, and beingheat-treated at 80° C., by five times, and thuspoly(2-bromoethyl)silsesquioxane is sufficiently loaded into pores ofthe porous sheet. The porous sheet is subjected to heat-treatment in anitrogen gas flow at 150° C. for one hour and at 450° C. for one hour.As a result, manufactured is a silica porous body having a nanostructurethat is transferred using the porous structure of the porous sheet as atemplate.

[0428] A mixed solution of acrylonitrile mixed with 10 wt % of3,3′,4,4′-tetra(t-butylperoxycarbonyl) benzophenone is prepared. Thesilica porous body is impregnated with the solution. The silica porousbody is irradiated with an ultraviolet ray, thereby polymerizing andcuring the acrylonitrile. The structure is heated in air at 210° C. for24 hours, and then heated in a nitrogen gas flow from 210° C. to 800° C.at a rate of temperature rise of 10° C. per minute so as to becarbonized. The composite of silica and carbon is treated withhydrofluoric acid to solve out the silica. As a result, it is possibleto manufacture porous carbon having continuous pores reflecting themorphology of the 1,2-polybutadiene porous sheet.

Example 43

[0429] Synthesis of Diblock Copolymer:

[0430] In this example, a diblock copolymer consisting ofpolycyclohexadiene derivative polymer chain(poly(cis-5,6-bis(pivaloyloxy)-2-cyclohexen-1,4-ylene)) and polyethyleneoxide (PEO) chain is synthesized by anion polymerization.

[0431] N-butyl lithium is employed as a reaction initiator. Employedethylene oxide is dried by passing through the column of calciumhydride, and then, is distilled after a small amount of n-butyl lithiumis added. Tetrahydrofuran (THF) used as a solvent is distilled twiceusing metallic sodium as a desiccating agent under an argon gas flow. Asa polymerization apparatus, a pressure reactor (Taiatsu Glass Co., Ltd.)is employed. The reaction is carefully performed in argon atmosphereunder a pressure of 4 atm so as to prevent an external air from enteringthe interior of the reaction system.

[0432] Poly(cis-5,6-bis(pivaloyloxy)-2-cyclohexen-1,4-ylene is chargedinto the reactor, and then THF is introduced into the reactorimmediately after it is distilled. After the interior of the reactor ismade into an argon gas atmosphere, a solution of n-butyl lithium inheptane is introduced into the reactor at −80° C., and then the mixtureis stirred for one week. Subsequently, a predetermined quantity ofethylene oxide is introduced into the reactor, and the mixture isfurther stirred. After 2 mL of 2-propanol containing a small amount ofhydrochloric acid is added to the mixture to terminate the reaction, thereactor is opened. After the reaction solution is concentrated bythree-times, the reaction solution is dropped in a sufficient amount ofpetroleum ether, thereby allowing a polymer to reprecipitate. After thepolymer is separated by filtration, the polymer is dried in vacuum atroom temperature, thereby providing a diblock copolymer.

[0433] The poly(cis-5,6-bis(pivaloyloxy)-2-cyclohexen-1,4-ylene) unithas Mw of 65,000, the polyethylene oxide unit has Mw of 13,200, andMw/Mn is 1.5.

[0434] Pattern Formation:

[0435] A mixture of the resultant diblock copolymer mixed with 5 wt % of3,3′,4,4′-tetrakis(t-butylperoxy-carbonyl)benzophenone is dissolved inmethylene chloride at a concentration of 2 wt %, followed by filtering,and then the solution is applied to a quartz glass substrate having adiameter of 3 inches by spin coating at a rate of 2,500 rpm to form apattern forming film. The substrate is heated at 110° C. for 90 secondsto evaporate the solvent. Thereafter, the substrate is placed in an ovenand then heat-treated in a nitrogen atmosphere at 150° C. for 5 hours,at 200° C. for 5 hours, at 300° C. for 5 hours and at 350° C. for 30minutes. When the surface of the substrate after heat-treatment isobserved with AFM, it is found that holes having a diameter of 12 nm areformed over the entire surface of the pattern forming film.

[0436] Reactive ion etching is performed under the conditions of CF₄,0.01 Torr, 150 W of progressive wave, and 30 W of reflected wave to etchthe substrate. Thereafter, reactive ion etching is performed under theconditions of O₂, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave to remove the residue of the pattern forming film. Underthe conditions, only the organic substances can be efficiently ashed. Asa result, holes having a diameter of 12 nm and a depth of 25 nm areformed over the entire surface of the quartz substrate at a density ofabout 2000/μm² and at approximately equal intervals.

[0437] A CoPtCr thin film having a thickness of 15 nm is deposited overthe entire surface of the quartz substrate by sputtering. Carbon havinga thickness of 10 nm is deposited as a protective film on the CoPtCrthin film by sputtering, from which anomalous projections are removed bytape vanishing, and then a lubricant is applied thereto to manufacture ahigh-density magnetic recording medium. The medium has perpendicularmagnetic anisotropy of 2 kOe.

Example 44

[0438] Synthesis of Diblock Copolymer:

[0439] In this example, a diblock copolymer consisting ofpolybutylmethylsilane chain and polyethylene oxide chain is synthesizedby living anion polymerization.

[0440] A masked disilene represented by the following chemical formulaand ethylene oxide are employed as monomers and sec-butyl lithium isemployed as a polymerization initiator, and these monomers aresuccessively introduced into in THF at a reaction temperature of −78° C.to synthesize the diblock copolymer. The weight-average molecularweights of respective blocks constituting the diblock copolymer are65,000 for polybutylmethylsilane and 13,200 for polyethylene oxide. Inaddition, molecular weight distribution (Mw/Mn) is 1.1.

[0441] Pattern Formation:

[0442] A 3-inch silicon wafer is spin-coated with a solution of polyamicacid (that is prepared by diluting Semicofine SP-341 available fromToray Co., Ltd. with N-methyl-2-pyrrolidone). Thereafter, the sample isheated under a nitrogen gas flow successively at 150° C., at 250° C. andat 350° C., for one hour, respectively, thereby forming a patterntransfer film consisting of polyimide having a thickness of 30 nm.

[0443] The synthesized diblock copolymer is dissolved in THF at aconcentration of 2 wt %, followed by filtering, and then the solution isapplied to the pattern transfer film made of polyimide by spin coatingat a rate of 2500 rpm, thereby forming a pattern forming film. Thesample is heated at 110° C. for 90 seconds to evaporate the solvent.Thereafter, the sample is placed in an oven and is heat-treated in anitrogen atmosphere at 150° C. for 5 hours. Then, the sample isirradiated with an ultraviolet ray from a low-pressure mercury lamp inair. The sample is placed again in the oven and is heat-treated in anitrogen atmosphere at 150° C. for one hour, at 200° C. for 5 hours, at300° C. for 5 hours, and at 350° C. for 30 minutes. When the surface ofthe substrate is observed with AFM, it is found that holes having adiameter of about 13 nm are formed over the entire surface of thepattern forming film.

[0444] Reactive ion etching is performed to the sample under theconditions of O₂, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave. As a result, holes having relatively high aspect ratioof a diameter of 13 nm and a depth of 30 nm are formed over the entiresurface of polyimide film (a pattern transfer film) on the silicon waferat a density of about 2000/μm² and at approximately equal intervals. RIEis performed under the conditions of CF₄, 0.01 Torr, 150 W ofprogressive wave, and 30 W of reflected wave using the polyimide porousfilm as an etching mask to etch the silicon wafer. Subsequently, ashingis performed under the conditions of O₂, 0.01 Torr, 150 W of progressivewave, and 30 W of reflected wave to etch the remaining polyimide film.As a result, holes of having a high aspect ratio of a diameter of 14 nmand a depth of 70 nm are formed over the entire surface of the siliconwafer at a density of about 2000/μm² and at approximately equalintervals.

[0445] From the results described above, it is found that a porous maskcan be formed from a diblock copolymer consisting of apolybutylmethylsilane chain and a polyethylene oxide chain, and that adot pattern having a high aspect ratio can be formed in the polyimidefilm as a pattern transfer film, and further that the underlyingsubstrate can be preferably processed.

Example 45

[0446] Synthesis of Diblock Copolymer:

[0447] In this example, a diblock polymer (PEO-b-PDMSO) consisting of apolyethylene oxide (PEO) chain and a polydimethylsiloxane (PDMSO) chainis synthesized by living anion polymerization.

[0448] Using a polyethylene oxide macromer as a reaction initiator,hexamethylcyclotrisiloxane is polymerized. Tetrahydrofuran (THF) used asa solvent is distilled twice using metallic sodium as a desiccatingagent under an argon gas flow. The polyethylene oxide has an OH group atone terminal and is capped with methoxy group at the other terminal,which is freeze-dried from a solution in benzene immediately before use.As for the polymerization apparatus, a pressure reactor (Taiatsu GlassCo., Ltd.) is employed. The reaction is carefully performed in an argonatmosphere under pressure of 4 atm so as to prevent an external air fromentering the interior of the reaction system.

[0449] While flowing an argon gas, a solution of polyethylene oxidedissolved in dehydrated benzene is introduced into the reactor, and thesolution is freeze-dried in vacuum over 5 hours. Under vacuum, THF isdistilled and directly introduced into the reactor. The interior of thereactor is filled with an argon gas atmosphere again, to which n-butyllithium is added at 0° C., followed by stirring at 30° C. for one hour,and then hexamethylcyclotrisiloxane is added at 25° C. to the solutionwith stirring so as to be polymerized. A small amount of the reactionsolution is taken out to measure the molecular weight by GPC. Based onthe measured molecular weight, an amount of hexamethylcyclotrisiloxaneto be added to give a desired molecular weight is calculated and addedso to the solution. A series of these procedures are carefully performedunder a pressurized argon atmosphere so as to prevent an external airfrom entering the interior of the reaction system. After it is confirmedby GPC that a desired molecular weight is given, trimethylchlorosilaneis added to the solution to terminate the reaction, and then the reactoris opened. The reaction solution is concentrated by three-times, andthen the solution is dropped in a sufficient amount of petroleum etherto reprecipitate the polymer. The polymer is separated by filtration andthen is dried in vacuum at room temperature, thus the diblock copolymeris provided.

[0450] The polyethylene oxide has Mw of 65,000, the polydimethylsiloxane has Mw of 62,000, and Mw/Mn is 1.20.

[0451] Pattern Formation:

[0452] A 3-inch silicon wafer is spin-coated with a solution of polyamicacid (that is prepared by diluting Semicofine SP-341 available fromToray Co., Ltd. with N-methyl-2-pyrrolidone (NMP)). The sample is heatedunder a nitrogen gas flow successively at 150° C., at 250° C. and at350° C., for one hour, respectively, thereby forming a pattern transferfilm consisting of polyimide having a thickness of 30 nm.

[0453] A mixture prepared by mixing the synthesized diblock copolymerwith 1,3,5,7,9,11,13-heptacyclopentyl-15-vinylpentacyclo[9.5.1.1^(3,9).1^(5,15).1^(7,13)] octasiloxane (Vinyl-POSS) andazobisisobutyronitrile in a weight ratio of 1:1:0.05 is dissolved in THFat a concentration of 2-wt %, followed by filtering. The solution isapplied to the pattern transfer film made of polyimide by spin coatingat a rate of 2500 rpm, thereby forming a pattern-forming film. Thesample is heated at 60° C. for 90 seconds to evaporate the solvent. Thesample is heat-treated a nitrogen atmosphere at 80° C. for 5 hours.Thereafter, the pattern-forming film is exposed to hydrochloric acidvapor. Then, the sample is heat-treated in a nitrogen atmosphere at 200°C. for one hour, at 250° C. for one hour, at 300° C. for one hour, andat 350° C. for 30 minutes. When the surface of the sample is observedwith AFM, it is found that holes having a diameter of about 15 nm areformed over the entire surface of the pattern forming film.

[0454] Reactive ion etching is performed to the sample under theconditions of O₂, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave. As a result, holes having a relatively high aspect ratioof a diameter of 15 nm and a depth of 30 nm are formed over the entiresurface of polyimide film (a pattern transfer film) on the silicon waferat approximately equal intervals. RIE is performed using the polyimideporous film as a mask under the conditions of CF₄, 0.01 Torr, 150 W ofprogressive wave, and 30 W of reflected wave to etch the silicon wafer.Subsequently, ashing is performed under the conditions of O₂, 0.01 Torr,150 W of progressive wave, and 30 W of reflected wave to remove theremaining polyimide film. As a result, holes having a high aspect ratioof a diameter of 14 nm and a depth of 70 nm are formed over the entiresurface of the silicon wafer at approximately equal intervals.

Example 46

[0455] Pattern Formation:

[0456] A mixture of the diblock copolymer comprising polyethylene oxideand polydimethylsiloxane synthesized in Example 45 and polyamic acidsynthesized from biphenyltetracarboxylic acid dianhydride andp-phenylene diamine in a weight ratio of 1:1 is dissolved in THF at aconcentration of 2 wt %, followed by filtering. The solution is appliedto a 3-inch silicon wafer by spin coating at a rate of 2500 rpm to forma pattern forming film. The sample is heated at 60° C. for 90 seconds toevaporate the solvent, and then is heat-treated in a nitrogen atmosphereat 80° C. for 5 hours. Thereafter, the pattern-forming film is exposedto hydrochloric acid vapor. Then, the sample is heat-treated in anitrogen atmosphere at 200° C. for one hour, at 250° C. for one hour, at300° C. for one hour, and at 350° C. for 30 minutes. When the surface ofthe sample is observed with AFM, it is found that holes having adiameter of 15 nm are formed over the entire surface of the patternforming film.

[0457] RIE is performed using the porous film as an etching mask underthe conditions of CF₄, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave to etch the silicon wafer. Thereafter, ashing of theremaining polymer is performed under the conditions of O₂, 0.01 Torr,150 W of progressive wave, and 30 W of reflected wave. As a result,holes having a diameter of 14 nm and a depth of 5 nm are formed over theentire surface of the silicon wafer at approximately equal intervals.

Example 47

[0458] Synthesis of Diblock Copolymer:

[0459] In this example, a triblock copolymer (PAN-PEO-PAN) consisting ofpolyethylene oxide (PEO) chain and polyacrylonitrile (PAN) chains issynthesized by living anion polymerization. Using a polyethylene oxidemacromer (disodium salt of polyethylene oxide) as a reaction initiator,acrylonitrile is polymerized. Tetrahydrofuran and benzene used assolvents are distilled twice using lithium aluminum hydride as adesiccating agent under an argon gas flow, to which molecular sieves 4Ais charged. The acrylonitrile employed as a monomer is washedsuccessively with a saturated aqueous solution of NaHSO₃, a saturatedaqueous solution of NaCl containing 1% of NaOH, and a saturated aqueoussolution of NaCl, and then vacuum-distilled using calcium chloride as adesiccating agent, and further vacuum-distilled using calcium hydride asa desiccating agent under an argon gas flow, to which molecular sieves4A is charged. Sodium naphthalene is prepared by reacting naphthalenewith metallic sodium in THF. Crown ether (dicyclohexyl-18-crown-6) isfreeze-dried from a solution in benzene, and then is dissolved inbenzene. Polyethylene oxide, which has OH groups at both ends, isfreeze-dried from a solution in benzene immediately before use. AS forthe polymerization apparatus, a pressure reactor (Taiatsu Glass Co.,Ltd.) is employed. The reaction is carefully performed in an argonatmosphere under pressure of 4 atm so as to prevent an external air fromentering the interior of the reaction system.

[0460] A solution of polyethylene oxide dissolved in dehydrated benzeneis introduced into the reactor with flowing an argon gas, and isfreeze-dried in vacuum over 5 hours. THF distilled under vacuum isdirectly introduced into the reactor. After the interior of the reactoris made into an argon gas atmosphere again, sodium naphthalene isintroduced into the reactor at 0° C., and further a solution of crownether in benzene is introduced at 30° C. with stirring. After themixture is stirred for one hour, acrylonitrile is added to the mixtureat −78° C. and allowed to polymerize with stirring. A small amount ofreaction solution is taken out to measure the molecular weight thereofby GPC. Based on the measured molecular weight, an amount ofacrylonitrile to be added to give a desired molecular weight iscalculated and added so to the solution. A series of these proceduresare carefully performed under a pressurized argon atmosphere so as toprevent an external air from entering the interior of the reactionsystem. After it is confirmed by GPC that a desired molecular weight isgiven, 2 mL of 2-propanol is added to the solution to terminate thereaction, and then the reactor is opened. The reaction solution isconcentrated by three-times and then is dropped in a sufficient amountof petroleum ether to reprecipitate a polymer. After the polymer isseparated by filtration, the polymer is vacuum-dried at roomtemperature, thus the triblock copolymer is provided.

[0461] The polyacrylonitrile has Mw of 65,000, the polyethylene oxidehas Mw of 13,200, and Mw/Mn is 1.40.

[0462] Pattern Formation:

[0463] A 2-wt % solution of resultant PAN-PEO-PAN triblock copolymer isfiltered, and then the solution is applied to a 3-inch quartz glasssubstrate by spin coating at a rate of 2,500 rpm to form a patternforming film. The sample is heated at 110° C. for 90 seconds toevaporate the solvent. Thereafter, the sample is placed in an oven andis heat-treated in a nitrogen atmosphere at 200° C. for 10 minutes,subsequently at 135° C. for 10 hours. The heat treatment at 200° C.flattens the film and can eliminate the histeresis after thespin-coating. In addition, the heat treatment at 135° C. can efficientlyadvance microphase separation. The sample is heat-treated in air at 200°C. for 24 hours, and then is heat-treated in a nitrogen atmosphere at350° C. for 30 minutes. When the surface of the substrate after the heattreatments is observed with AFM, it is found that holes having adiameter of about 12 nm are formed over the entire surface of thepattern forming film.

[0464] Reactive ion etching is performed to the sample under theconditions of CF₄, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave to etch the substrate. Thereafter, reactive ion etchingis performed under the conditions of O₂, 0.01 Torr, 150 W of progressivewave, and 30 W of reflected wave to remove the residue of the patternforming film.

[0465] As a result, holes having a diameter of 12 nm and a depth of 20nm are formed over the entire surface of quartz glass substrate at adensity of about 2000/m² and at approximately equal intervals. Thesubstrate can be used as a substrate for a hard disk.

Example 48

[0466] Ten wt % of dioctyl phthalate is added as a plasticizer to thePAN-PEO-PAN triblock copolymer synthesized in Example 47. Heat-treatmentconditions for forming microphase separation of the block copolymer isset to: under a nitrogen gas flow at 200° C. for 10 minutes,subsequently at 135° C. for one hour, in air at 200° C. for 24 hours,and then under a nitrogen gas flow at 350° C. for 30 minutes. A filmhaving micro polymer phases is formed in a similar manner to that inExample 47 except for these conditions. The sample is etched using thefilm having micro polymer phases as a mask. As a result, a patternsimilar to that in Example 47 can be formed in the substrate. Asdescribed above, addition of the plasticizer can shorten theheat-treating time.

Example 49

[0467] A 2-wt % solution of PAN-PEO-PAN triblock copolymer synthesizedin Example 47 is filtered, and then the solution is applied to a 3-inchquartz glass substrate by spin coating at a rate of 2,500 rpm to form apattern forming film. The sample is heated at 110° C. for 90 seconds toevaporate the solvent. The sample is placed in an oven and isheat-treated in a nitrogen atmosphere at 200° C. for 10 minutes and at135° C. for 10 hours. The sample is heat-treated in air for 24 hours at200° C., and then is heat-treated in a nitrogen atmosphere at 350° C.for 30 minutes. Next, the substrate is etched with hydrofluoric acid forone minute. Thereafter, ultrasonic washing is performed in acetone toremove the remaining polymer.

[0468] As a result, holes having a diameter of 15 nm and a depth of 12nm are formed over the entire surface of quartz glass substrate at adensity of about 2000/μm² and at approximately equal intervals. In sucha manner, the substrate can be patterned with only wet etching withoutusing a dry etching process. The substrate can be used as a substratefor a hard disk.

Example 50

[0469] Synthesis of Diblock Copolymer:

[0470] Using polyethylene oxide having a methoxy group at one terminaland having an OH group at the other terminal, a diblock polymer(PAN-b-PEO) consisting of a polyethylene oxide (PEO) chain and apolyacrylonitrile (PAN) chain is synthesized by living anionpolymerization by a similar method to that in Example 47. Thepolyacrylonitrile has Mw of 10,600, the polyethylene oxide has Mw of35,800, and Mw/Mn is 1.37.

[0471] Pattern Formation:

[0472] A CoPtCr magnetic film is formed on a quartz glass substrate. Apattern forming film made of the above diblock copolymer is formed onthe magnetic film, and then the pattern forming film is allowed to forma structure having micro polymer phases. Thereafter, the CoPtCr magneticfilm is subjected to wet etching in a similar manner to that in Example49. As a result, formed is a magnetic film structure in whichprojections having a diameter of 15 nm and a height of 12 nm are formedover the entire surface of quartz glass substrate at a density of about1800/μm² and at approximately equal intervals.

Example 51

[0473] A quartz substrate is spin-coated with a solution of polyamicacid (that is prepared by diluting Semicofine SP-341 available fromToray Co., Ltd. with N-methyl-2-pyrrolidone). The substrate is heatedunder a nitrogen gas flow subsequently at 150° C., at 250° C. and at350° C., respectively, for one hour, to form a lower pattern transferfilm consisting of polyimide having a thickness of 500 nm. Aluminum isdeposited thereon to a thickness of 15 nm to form an upper patterntransfer film. The PAN-PEO-PAN triblock copolymer synthesized by thesimilar method to that in Example 47 is applied thereto in a thicknessof 80 nm spin-coated to form a pattern forming film. Thepolyacrylonitrile block has Mw of 144,600, the polyethylene oxide has Mwof 70,700, and Mw/Mn is 1.41. Then, a porous pattern forming film havinga structure having micro polymer phases is manufactured by the samemethod as in Example 47.

[0474] Reactive ion etching is performed to the sample under theconditions of CF₄, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave, to transfer the phase-separated pattern of the patternforming film to the upper pattern transfer film made of aluminum.Subsequently, reactive ion etching is performed to the sample under theconditions of O₂, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave, to remove the residue of the pattern forming film, andat the same time, to etch the lower pattern transfer film formed ofpolyimide that are exposed to outside through openings in the upperpattern transfer film. Further, reactive ion etching is performed underthe conditions of CF₄, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave, to remove the upper pattern transfer film, and at thesame time, to etch a part of the quartz substrate exposed through theopenings formed in the pattern transfer film. Reactive ion etching isperformed again under the conditions of O₂, 0.01 Torr, 150 W ofprogressive wave, and 30 W of reflected wave, to remove the lowerpattern transfer film. As a result, holes having a very high aspectratio of a diameter of 110 nm and a depth of 1200 nm are formed over theentire surface of the quartz substrate at a density of 35/μm².

Example 52

[0475] A SiO₂ film having a thickness of 500 nm is formed on a siliconwafer. A solution of polysilane represented by the following chemicalformula (Mw=12,000, x=0.4) in toluene is applied to the SiO₂ film,followed by baking, thereby manufacturing a polysilane pattern transferfilm having a thickness of 100 nm. To the polysilane transfer film, 0.5wt % of 3,5-di-tert-butyl-4-hydroxy toluene is added as an antioxidant.

[0476] The pattern transfer film consisting of polysilane is coated witha diblock copolymer consisting of polyacrylonitrile (Mw=12,000) andpolyethylene oxide (Mw=28,000) synthesized by the same method as that inExample 50, followed by baking at 90° C. for two minutes, to form apattern forming film having a thickness of 40 nm. The sample is placedin an oven, and heat-treated in a nitrogen atmosphere at 200° C. for 10minutes and then at 135° C. for 10 hours, and in air at 200° C. for 24hours, and further in a nitrogen atmosphere at 350° C. for 30 minutes.

[0477] The polysilane film is etched using the pattern forming film as amask under the conditions of HBr flow rate of 50 sccm, vacuum degree of80 mTorr and excitation power of 200 W. As a result, the pattern can betransferred to the polysilane film. Since the pattern forming film isleft remained on the polysilane film, it is found that the patternforming film has sufficient etch resistance. Then, the SiO₂ film isetched using the polysilane film pattern as a mask under the conditionsof C₄F₈ flow rate of 50 sccm, CO flow rate of 10 sccm, Ar flow rate of100 sccm, O₂ flow rate of 3 sccm, vacuum degree of 10 mTorr, andexcitation power of 200 W. The polysilane film has sufficient etchresistance, so that the pattern can be preferably transferred to theSiO₂ film. The remaining polysilane film can be easily removed using anaqueous organoalkali solution or a diluted hydrofluoric acid solution.

[0478] Incidentally, when the same procedures as described above areperformed without addition of 3,5-di-tert-butyl-4-hydroxy toluene to thepolysilane transfer film, etching selectivity between the patternforming film and the polysilane pattern transfer film is reduced by 30%.

Example 53

[0479] A gold electrode is deposited on a glass substrate having adiameter of 10 inches, a SiO₂ film having a thickness of 100 nm isformed thereon, and an aluminum film having a thickness of 50 nm isdeposited thereon.

[0480] A diblock copolymer (polyacrylonitrile: Mw=127,700, polymethyleneoxide: Mw=1,103,000; Mw/Mn=1.30) and polyacrylonitrile (Mw=45,000,Mw/Mn=1.37) are mixed at the weight ratio of 21:79. The mixture isdissolved in acetonitrile by 5 wt %, followed by filtering, to prepare asolution. The solution is applied to the quartz glass substrate by spincoating and dried at 110° C. to form a pattern forming film having athickness of 970 nm.

[0481] The sample is placed in an oven and heat-treated in a nitrogenatmosphere at 210° C. for 10 minutes and then at 135° C. for 10 hours,and in air at 200° C. for 24 hours, and further in a nitrogen atmosphereat 350° C. for 30 minutes, to make the pattern-forming film porous.

[0482] The sample is subjected to wet etching with an aqueous solutionof hydrochloric acid and then by hydrofluoric acid, thereby transferringthe phase-separated pattern of the pattern forming layer to the aluminumlayer as well as to the SiO₂ layer. Thereafter, ashing is performed withan asher to remove the residue of pattern forming layer.

[0483] As a result, holes having a diameter of about 840 nm can beformed in the aluminum layer and SiO₂ layer at a density of about 23,000per unit area of 300 μm×100 μm. The size distribution of holes is veryuniform within the range of +10%. This is because the block copolymeruniform in molecular weight is used. Also, since the islands of blockcopolymer are present in the sea of the homopolymer, holes are formed atrandom positions in some degree. Thus, if the sample is used as a porousgate electrode of a field emission display (FED) of three-electrodestructure, it is expected that interference fringe due to regularity ofelectrodes can be prevented from occurring. Therefore, the method ofthis example can be suitably applied to the manufacture of porous gateelectrode of FED.

Example 54

[0484] Dioctyl phthalate as a plasticizer is added by 10 wt % to themixture in Example 53 of the diblock copolymer and the polyacrylonitrilehomopolymer. The heat-treatment conditions for form microphaseseparation are set to as follows: under a nitrogen gas flow at 200° C.for 10 minutes and then at 135° C. for one hour, and in air at 200° C.for 24 hours, and further under a nitrogen gas flow at 350° C. for 30minutes. A film having micro polymer phases is formed in a similarmanner to that in Example 53 except for these conditions. Etching isperformed using the film having micro polymer phases. As a result, apattern of holes same as that in Example 53 can be formed in thesubstrate. As described above, addition of the plasticizer can shortenthe heat treatment time.

Example 55

[0485] Gold is sputtered on the surface of a copper plate. A 10%solution of a diblock copolymer (polymethylphenylsilane Mw=135,000,PMMA: Mw=61,000, Mw/Mn=1.10) in PGMEA is applied to the gold film, andthen dried over 9 days in a desiccator. The resultant film has athickness of 0.2 mm. The film is vacuum-dried for 3 days. An ultra-thinfilm is cut out from this film, which is observed with a transmissionelectron microscope. As a result, it is confirmed that formed is athree-dimensional bicontinuous structure in which both the polysilanephase and the PMMA phase are formed continuously.

[0486] The sample is irradiated with an electron beam at an exposuredose of 150 kGy, and the is heat-treated in air at 150° C. for 2 hoursand at 200° C. for 12 hours, and further under an argon gas flow at 500°C. for one hour. When the film is observed with a transmission electronmicroscope (TEM), it is observed that the PMMA phase is eliminated andthe polysilane phase forms a continuous structure in the form of asponge. The structure is almost same as the original three-dimensionalbicontinuous structure, in which continuous pores of the order ofnanometers are formed regularly.

[0487] Copper electroplating is performed using the copper plate onwhich the porous film is formed as a working electrode, another copperplate as a counter electrode, and a saturated calomel electrode as areference electrode. A saturated aqueous solution of copper sulfate isemployed as an electrolyte solution, and electrolysis voltage is set to−0.1V vs SCE. As a result, a nanocomposite film having a porous film inwhich pores are filled with copper is manufactured.

Example 56

[0488] Synthesis of a Polysilane-Polyethylene Oxide Diblock Copolymer:

[0489] As monomers, a masked disilene and ethylene oxide are employed.As a polymerization initiator, sec-butyl lithium is employed. Thesemonomers are successively introduced into THF at a reaction temperatureof −78° C., and thus a diblock copolymer comprising apolybutylmethylsilane chain and a polyethylene oxide chain issynthesized by living anion polymerization. The diblock copolymer has Mwof 70,500 and Mw/Mn of 1.2, the polysilane unit has Mw of 14,500, andthe polyethylene oxide unit has Mw of 56,000.

[0490] A quartz substrate is spin-coated with a solution of polyamicacid (that is prepared by diluting Semicofine SP-341 available formToray Co., Ltd. with N-methyl-2-pyrrolidone). The substrate is heatedunder a nitrogen gas flow at 150° C., at 250° C. and at 350° C.,respectively, for one hour, to form a polyimide film (a pattern transferfilm). The polyimide film is coated with a solution of the diblockcopolymer synthesized as described above to form a pattern forming film.The pattern forming film is irradiated with an ultraviolet ray from ahigh-pressure mercury lamp to photo-oxidize the polysilane chain. Thesample is heat-treated in air at 150° C. for one hour, and in a nitrogenatmosphere at 200° C. for 2 hours, at 250° C. for 2 hours, and at 350°C. for 30 minutes to make the film porous. Reactive ion etching isperformed using the porous film as a mask under the conditions of O₂,0.01 Torr, 150 W of progressive wave, and 30 W of reflected wave. Atthis time, the photo-oxidized polysilane film has sufficient etchresistance, making it possible to transfer a preferable pattern to thepolyimide film. Further, the substrate is etched using the polyimidefilm as a mask. As a result, holes having a diameter of 14 nm and adepth of 10 nm are formed over the entire surface of the substrate at adensity of about 2400/μm² and at approximately equal intervals.

Example 57

[0491] The same diblock copolymer as employed in Example 43 is dissolvedby 1 wt % in methylene chloride. To the solution, 1 wt % oftetrabutylammonium hexachloro-platinate (IV) based on the weight of thepolymer is added. The solution is cast on a SiO substrate to form apattern forming film having a thickness of 20 nm. The sample is heatedat 110° C. for 90 seconds to evaporate the solvent. Thereafter, thesample is placed in an oven and is heat-treated in a nitrogen atmosphereat 150° C. for 5, at 200° C. for 5 hours, at 300° C. for 5 hours and at350° C. for 30 minutes.

[0492] Reactive ion etching is performed to the sample under theconditions of CF₄, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave to etch the SiO substrate. As a result, holes having adiameter of 12 nm and a depth of 25 nm are formed over the entiresurface of the SiO substrate at a density of about 2000/μm² and atapproximately equal intervals. Further, platinum particles are depositedin the holes. By allowing a magnetic material to grow using thedeposited platinum particles as nuclei, a magnetic recording medium ofhard disk can be manufactured.

Example 58

[0493] Synthesis of Graft Copolymer:

[0494] Styrene-terminated polyethylene oxide macromer (a) (Mw=14,100,Mw/Mn=1.04) and polysilsesquioxane derivative monomer (b) (where R is ahexyl group), represented by the following chemical formulas,respectively, are dissolved in THF, to which AIBN as a radical initiatoris added, and then the mixture is heated in an argon atmosphere at 60°C. for 60 hours to synthesize a graft copolymer by radicalpolymerization. The graft copolymer has Mw of 101,000 and Mw/Mn of 2.1,the polysilsesquioxane derivative unit has Mw of 16,400, and thepolyethylene oxide macromer unit has Mw of 84,600.

[0495] The graft copolymer is dissolved by 2 wt % in ethyl lactate,which is applied to a substrate and the naturally dried to form apattern forming film. The sample is heated at 110° C. for 90 seconds toevaporate the solvent. The sample is heat-treated at 200° C. for onehour and at 350° C. for 5 hours to make the pattern forming film porous.Reactive ion etching is performed to the sample under the conditions ofCF₄, 0.01 Torr, 150 W of progressive wave, and 30 W of reflected wave toetch the substrate. As a result, many projections having a diameter of18 nm and a height of 10 nm are formed on the substrate.

Example 59

[0496] A 10% solution of a diblock copolymer (polyacrylonitrileMw=137,000, polypropylene oxide Mw=32,000, Mw/Mn=1.45) in PGMEA ispoured into a Teflon Petri dish, and then dried in a desiccator under anargon gas flow over 9 days. The thickness of the formed film is 0.2 mm.The film is vacuum-dried for 3 days. An ultra-thin film is cut out fromthe film, which is observed with a transmission electron microscope. Asa result, it is confirmed that formed is a cylindrical structure inwhich cylindrical polypropylene oxide phases are formed in the matrix ofthe polyacrylonitrile phase.

[0497] The sample is irradiated with an electron beam at an exposuredose of 20 kGy. The sample is heat-treated in air at 150° C. for 2 hoursand at 200° C. for 12 hours, and under an argon gas flow at 500° C. forone hour and at 1200° C. for one hour. When the sample is observed withTEM, it is found that formed is porous carbon in the form of a honeycombretaining the cylindrical structure having pores with a diameter ofabout 20 nm. The porous carbon can be preferably employed as a carbonelectrode.

[0498] When porous carbon is manufactured in the same manner asdescribed above except that polyacrylonitrile-propylene oxide diblockcopolymer (polyacrylonitrile Mw=69,000, polypropylene oxide Mw=14,000,Mw/Mn=1.42) is employed as a diblock copolymer. In this case, the porouscarbon has pores with a diameter of about 9 nm.

Example 60

[0499] A 10% solution of a diblock copolymer (polyacrylonitrileMw=137,000, polypropylene oxide Mw=62,000, Mw/Mn=1.45) in PGMEA ispoured into a Teflon Petri dish, and then dried in a desiccator under anargon gas flow over 9 days. The thickness of the formed film is 10 μm.The film is vacuum-dried for 3 days. An ultra-thin film is cut out fromthe film, which is observed with a transmission electron microscope. Asa result, it is confirmed the formed is a three-dimensional bicontinuousstructure in which both the polyacrylonitrile phase and thepolypropylene oxide phase are formed continuously.

[0500] The sample is irradiated with an electron beam at an exposuredose of 20 kGy. The film is heat-treated in air at 150° C. for 2 hoursand at 200° C. for 12 hours, and under an argon gas flow at 500° C. forone hour and at 1200° C. for one hour. TEM observation shows that porouscarbon retaining a bicontinuous structure is formed. The porous carboncan be preferably employed as a carbon electrode.

Example 61

[0501] A 10% solution of a diblock copolymer A (polyacrylonitrileMw=68,000, polypropylene oxide Mw=32,000, Mw/Mn=1.45) is poured into aTeflon Petri dish, and then is dried over 9 days in a desiccator tomanufacture a film. Platinate chloride and ruthenium chloride(Pt/Ru=1:1) are added to the solution of the diblock copolymer A.Likewise, a 10% solution of a diblock copolymer B (polyacrylonitrileMw=137,000, polypropylene oxide Mw=62,000, Mw/Mn=1.45) is poured into aTeflon Petri dish, and then is dried over 9 days in a desiccator tomanufacture a film. These films thus manufactured have a thickness of 10μm, respectively. The films are vacuum-dried for 3 days. Ultra-thinfilms are cut out from these films, respectively, which are observedwith a transmission electron microscope. As a result, it is confirmedthat these films has a structure having micro polymer phases in which apolyacrylonitrile phase and a polypropylene oxide phase are entangledwith each other. The diblock copolymer A is treated with formalin togenerate Pt particles and Ru particles.

[0502] A solution of polyamic acid (that is prepared by dilutingSemicofine SP-341 available from Toray Co., Ltd. withN-methyl-2-pyrrolidone) is applied to a silicon wafer with anapplicator, immediately after that wafer is placed in a large amount ofpure water so as not to evaporate the solvent and is immersed in waterfor 5 hours. The film is vacuum-dried at 50° C. for 8 hours, and furthervacuum-dried at 170° C. for 8 hours. Next, the film is heat-treated in anitrogen gas atmosphere at 200° C., at 250° C., at 300° C. and at 350°C., respectively, for one hour, to provide a three-dimensional porouspolyimide film having an average pore size of about 0.5 μm.

[0503] The diblock copolymer A film, the diblock copolymer B film andthe porous polyimide film are laminated and pressed to each other. Thelaminate is heat-treated in air at 150° C. for 2 hours and at 200° C.for 12 hours, and further under an argon gas flow at 500° C. for onehour and at 1200° C. for one hour. TEM observation of the cross-sectionof the sample shows that three-layered porous carbon laminate eachhaving a pore size of about 20 nm, 40 nm and 0.1 to 0.5 μm,respectively.

[0504] On the other hand, to the diblock copolymer B (polyacrylonitrileMw=137,000, polypropylene oxide Mw=62,000, Mw/Mn=1.45), a colloidalsolution containing Pt fine particles having an average particle size of5 nm that are generated using the diblock copolymer B as a coagulationinhibitor is added, and then a cast film having a thickness of 10 μm isformed. Pt fine particles are segregated at the interface of thestructure having micro polymer phases of the diblock copolymer B. Thecast film is heat-treated in air at 150° C. for 2 hours and at 200° C.for 12 hours, and further under an argon gas flow at 500° C. for onehour and at 1200° C. for one hour to manufacture a Pt-dispersed porouscarbon film.

[0505] An electrolyte film consisting of Naphyon 117 (DuPont Co., Ltd.)having a thickness of 50 μm is formed on the porous layer having thepore size of 20 nm among the three layers of the porous carbon laminatefilm employed as a methanol fuel electrode, and then the Pt-dispersedporous carbon film as an air electrode is laminated thereon, therebymanufacturing a thin direct methanol fuel cell having a thickness of assmall as 0.1 μm. When methanol and air are supplied to the cell so as toactuate the cell at 60° C., a continuous power generation is confirmed.

Example 62

[0506] 3.5 g of polyoxyethylene (23) lauryl ether (Wako Junyaku KogyoCo., Ltd.) as a surfactant, 0.2 g of glycerin, 3.4 g of furfuryl alcoholas a precursor of a thermosetting resin and 1.1 g of hydrochloric acidare dissolved in 29 g of water. To the aqueous solution, 33 g ofisooctane is added and vigorously stirred and then the mixture isreacted at 60° C. for one month. The reaction mixture is filtered andthe precipitate is separated out and washed with water and dried invacuum to provide 11.0 g of black carbon precursor powder. The powder isfired in air at 200° C. for 2 hours and subsequently under a nitrogengas flow at 500° C. for one hour to provide 0.4 g of carbon structure.

[0507]FIGS. 11 and 12 show SEM photographs of the carbon structures. Asshown in FIGS. 11 and 12, the carbon structures have a complex structurethat is spherical as a whole and has circular structures on the surfacethereof.

[0508] When the reaction and firing are performed in the same manner asdescribed above except that 0.2 g of a 20 wt % solution of titaniumtrichloride in hydrochloric acid is added to the above aqueous solution.In this case, 0.8 g of the carbon structure is obtained. In such amanner, addition of titanium trichloride can improve the yield.

Example 63

[0509] Synthesis of Diblock Copolymer:

[0510] A diblock polymer consisting of 1,2-polybutadiene chain andpolyethylene oxide chain is synthesized by living anion polymerization.The 1,2-polybutadiene chain has Mw of 65,000, the polyethylene oxidechain has Mw of 13,200, and Mw/Mn is 1.1.

[0511] Pattern Formation:

[0512] A 2 wt % solution of a mixture prepared by adding 3 wt % of3,3′,4,4′-tetrakis(t-butylperoxycarbonyl) benzophenone to the resultantdiblock polymer is filtered. The solution is applied to a 3-inch quartzglass substrate by spin coating at a rate of 2,500 rpm to form a patternforming film. The sample is placed in an oven and is heat-treated in anitrogen atmosphere at 135° C. for 2 hours and at 170° C. for one hour.The heat-treatment at 170° C. allows the 1,2-polybutadiene chain to bethree-dimensionally cross-linked. Further, the sample is heat-treated ina nitrogen atmosphere at 170° C. for 30 minutes. When the surface of thesubstrate after the heat treatments is observed with AFM, it is foundthat holes having a size of about 13 nm are formed over the entiresurface of the pattern forming film.

[0513] Reactive ion etching is performed to the sample under theconditions of CF₄, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave. Thereafter, Reactive ion etching is performed to thesample under the conditions of O₂, 0.01 Torr, 150 W of progressive wave,and 30 W of reflected wave to remove the residue of the pattern formingfilm.

[0514] As a result, holes having a diameter of 13 nm and a depth of 15nm are formed over the entire surface of quartz glass substrate at adensity of about 2000/μm² and at approximately equal intervals. A CoPtCrthin film having a thickness of 15 nm is deposited on the quartzsubstrate by sputtering. Carbon having a thickness of 10 nm is depositedas a protective film on the CoPtCr thin film by sputtering, from whichanomalous projections are removed by tape vanishing, and then alubricant is applied thereto to manufacture a high-density magneticrecording medium. The medium has perpendicular magnetic anisotropy of1.8 kOe.

Example 64

[0515] Pattern Formation:

[0516] A 2 wt % solution of a mixture that is prepared by adding 3 wt %of 3,3′,4,4′-tetrakis(t-butylperoxy-carbonyl)benzophenone is added tothe same diblock polymer as that employed in Example 63 is filtered. Thesolution is applied to a 3-inch quartz glass substrate by spin coatingat a rate of 2,500 rpm to form a pattern forming film. The sample isplaced in an oven and is heat-treated in a nitrogen atmosphere at 135°C. for 2 hours and at 170° C. for one hour. The heat-treatment at 170°C. allows the polybutadiene chain to be three-dimensionallycross-linked. Further, the sample is heat-treated in a nitrogenatmosphere at 170° C. for 30 minutes. When the surface of the substrateafter the heat treatments is observed with AFM, it is found that holeshaving a size of about 13 nm are formed over the entire surface of thepattern forming film.

[0517] Reactive ion etching is performed to the sample under theconditions of CF₄, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave. After etching, the substrate is further treated withhydrofluoric acid. The sample is immersed in a solution of tin (II)chloride (0.1 mL/L of 37% concentrated sulfuric acid is added to 1.0 g/Lof SnCl₂) for 20 seconds, and then the sample is washed with pure water.Subsequently, the sample is immersed in a solution of palladium chloride(0.1 mL/L of 37% concentrated sulfuric acid is added to 0.1 g/L ofPdCl₂) for 20 seconds, and then the sample is washed with pure water.These operations to immerse the sample into the solutions of tin (II)chloride and palladium chloride are repeated several times.

[0518] As a result, provided is a structure in which palladium dotshaving a diameter of about 10 nm are formed over the entire surface ofthe quartz glass substrate at a density of about 2000/μm² and atapproximately equal intervals. A CoPtCr thin film having a thickness of15 nm is deposited on the quartz substrate by sputtering. Carbon havinga thickness of 10 nm is deposited as a protective film on the CoPtCrthin film by sputtering, from which anomalous projections are removed bytape vanishing, and then a lubricant is applied thereto to manufacture ahigh-density magnetic recording medium.

[0519] The above dot-like palladium can also be used as a mask or as adotted electrode.

Example 65

[0520] Polyethylene oxide whose ends are treated with3,5-diaminobenzoate (weight-average molecular weight Mw=20,000) isreacted with paraphenylenediamine and pyromellitic anhydride tosynthesize polyamic acid having polyethylene oxide chains as graftchains. The weight ratio between the polyamic acid moiety and thepolyethylene oxide moiety is set to 1:2. One part by weight ofbis(4-maleimidophenyl)methane is added to 30 parts by weight of thesynthesized polyamic acid, and then a solution in N-methylpyrrolidone isprepared. The solution is applied to a glass plate using an applicatorto form a sheet having a thickness of 10 μm. The sheet is subjected toheat-treatment in a nitrogen flow at 150° C., 250° C. and 350° C. forone hour, respectively, to provide a porous sheet. The resultant poroussheet has a porous structure to which transferred is a bicontinuousphase-separated structure consisting of polybutadiene cylinder phaseshighly branched in a three-dimensional network configuration.

[0521] The resultant polyimide porous sheet is subjected to repeatingprocesses comprising steps of being impregnated with apoly(2-bromoethyl)silsesquioxane, being irradiated with an ultravioletray, and being heat-treated at 80° C., by five times, and thuspoly(2-bromoethyl)silsesquioxane is sufficiently loaded into pores ofthe porous sheet. The porous sheet is subjected to oxygen ashing underthe conditions of 800 W and 1 Torr. As a result, it is possible tomanufacture a silica porous body having a nanostructure that istransferred using the porous structure of the polyimide porous sheet asa template.

[0522] A mixed solution of acrylonitrile mixed with 10 wt % of3,3′,4,4′-tetra(t-butylperoxycarbonyl) benzophenone is prepared. Thesilica porous body is impregnated with the solution. The silica porousbody is irradiated with an ultraviolet ray, thereby polymerizing andcuring the acrylonitrile. The structure is heated in air at 210° C. for24 hours, and then heated in a nitrogen flow from 210° C. to 800° C. ata rate of temperature rise of 10° C. per minute so as to be carbonized.The composite of silica and carbon is treated with hydrofluoric acid tosolve out the silica. As a result, it is possible to manufacture porouscarbon having continuous pores reflecting the morphology of thepolyimide porous sheet.

Example 66

[0523] A block copolymer of PS having a molecular weight of 65,000 andPMMA having a molecular weight of 13,000, and platinum particles coveredwith PMMA are prepared. One wt % of the platinum particle-including PMMAis added to the block copolymer. The resultant mixture is dissolved inethyl cellosolve acetate to prepare a 10 wt % solution.

[0524] A SiO substrate having a diameter of 3 inches is spin-coated withthe solution at a rate of 2,500 rpm. The substrate is heated at 110° C.for 90 seconds to evaporate the solvent. The substrate is placed in anoven and the is annealed in a nitrogen atmosphere at 210° C. for 10minutes, subsequently at 135° C. for 10 hours. When the SiO substrate isobserved with an atomic force microscope in a phase mode, it isconfirmed that islands of PMMA having a diameter of about 17 nm areformed in the sea of PS.

[0525] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave to etch thePMMA selectively, and further to etch the exposed underlayer using theremaining PS pattern as a mask. Ashing is performed to the sample underthe conditions of O₂, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave to remove the mask made of PS.

[0526] It is observed with SEM and AFM that holes having a diameter ofabout 20 nm are formed over the entire surface of the 3-inch SiOsubstrate at approximately equal intervals. Also, it is observed thatthe platinum particles are aggregated at the center of the holes.

Example 67

[0527] A block copolymer of polystyrene having a molecular weight of26,000 and poly(2-vinylpyridine) having a molecular weight of 5,600,platinum particles covered with poly(2-vinylpyridine), and platinumparticles covered with polymethyl acrylate are prepared. The two kindsof platinum particle-including polymers are added by 1 wt %,respectively, to the block copolymer. The resultant mixture is dissolvedin diglyme to prepare a 10% solution.

[0528] A SiO substrate having a diameter of 3 inches is spin-coated withthe solution at a rate of 2,500 rpm. The substrate is heated at 110° C.for 90 seconds to evaporate the solvent. The substrate is placed in anoven and is annealed in a nitrogen atmosphere at 210° C. for 10 minutes,subsequently at 135° C. for 10 hours.

[0529] Ashing is performed to the entire surface of the sample under theconditions of O₂, 0.01 Torr, 150 W of progressive wave, and 30 W ofreflected wave to remove the block copolymer. As a result, only platinumparticles remain on the substrate.

[0530] It is observed with SEM and AFM that platinum particles having aparticle size of about 4 nm are dispersed with forming a trianglelattice of about 25 nm over the entire surface of the substrate.

[0531] After the surface of the substrate is lightly sputter-etched at100 W for one minute, CoPt is sputtered under a pressure of 2 Pa,thereby depositing a magnetic layer having a thickness of 20 nm withusing the platinum particles as seeds. The result of determination ofthe coercive force from the hysteresis curve shows 13 kOe.

[0532] For the purpose of comparison, a magnetic layer is deposited on aglass substrate on which metal fine particles are dispersed. Themagnetic layer has coercive force of 5 kOe.

Example 68

[0533] In place of platinum particles covered with poly(2-vinylpyridine)employed in Example 67, platinum particles covered with a blockcopolymer comprising PS having a molecular weight of 4,800 andpoly(2-vinylpyridine) having a molecular weight of 4,300 are employed.One wt % of the platinum particle-including block copolymer is added tothe block copolymer employed in Example 67. The resultant mixture isdissolved in ethyl cellosolve acetate to prepare a 10-wt % solution.

[0534] A SiO substrate having a diameter of 3 inches is spin-coated withthe solution at a rate of 2,500 rpm. The substrate is heated at 110° C.for 90 seconds to evaporate the solvent. The substrate is placed in anoven and is annealed in a nitrogen atmosphere at 210° C. for 4 hours,subsequently at 135° C. for 10 hours.

[0535] When the substrate is observed with an atomic force microscope ina phase mode, it is confirmed that islands of poly(2-vinylpyridine)having a size of about 17 nm are dispersed in the sea of PS in whichmetal fine particles locally exist at the interface between the islandsand the sea.

[0536] RIE is performed to the sample under the conditions of CF₄, 0.01Torr, 150 W of progressive wave, and 30 W of reflected wave to etch thepoly(2-vinylpyridine) selectively, and further to etch the exposedunderlayer using the remaining PS pattern as a mask. Ashing is performedto the sample under the conditions of O₂, 0.01 Torr, 150 W ofprogressive wave, and 30 W of reflected wave to remove the mask made ofPS.

[0537] It is observed with SEM and AFM that holes having a diameter ofabout 20 nm are formed over the entire surface of the 3-inch SiOsubstrate at approximately equal intervals. Also, it is observed thatthe platinum particles are segregated at the edges of the holes.

Example 69

[0538] Another method for manufacturing the field emission display (FED)device shown in FIG. 9 will be described. Similar to the method inExample 27, the cathode conductor 102 is formed on the insulativesubstrate 101, and then a portion of the cathode conductor 102 isetched. The resistance layer 103 formed to cover the cathode conductor102, and then the resistance layer 103 is patterned to form a pluralityof terminals 103A. The insulating layer 104 is formed to cover thecathode conductor 102 and the resistance layer 103, and then the gateconductor 105 is formed on the insulating layer 104.

[0539] Then, a resist is patterned to protect intersecting portionsbetween gate wires and emitter wires. A solution of a mixture of thePS-PMMA diblock copolymer used in Example 66 and platinum particlescoated with PMMA is applied to the gate conductor 105 by spin coatingand then dried, followed by annealing, thereby forming a film havingmicro polymer phases. RIE with CF₄ gas is performed to the film havingmicro polymer phases, thus the PMMA in the film having micro polymerphases is selectively etched, and further the gate conductor 105 isetched with using the pattern of remaining PS as mask, therebytransferring the pattern to the gate conductor 105. Thereafter, ashingis performed with an O₂ asher, thereby removing the remaining organicsubstances. In such a manner, many openings 106 having a diameter ofabout 840 nm are formed in the gate conductor 105. Wet etching with abuffered hydrofluoric acid (BHF) or RIE with a gas such as CHF₃ isperformed to remove the insulating layer 104 in the openings 106 untilthe resistance layer 103 is exposed to the outside. As a result, it isconfirmed that platinum particles are deposited on the bottom of theopenings 106.

[0540] Then, aluminum is obliquely deposited by electron beam (EB)evaporation to form a peeling layer. Molybdenum is normally deposited onthe peeling layer in the perpendicular direction by EB evaporation,thereby depositing molybdenum in a conical configuration inside theopenings 106 to form the emitters 107. Thereafter, the peeling layer isremoved with a peeling solution such as phosphoric acid, therebymanufacturing an FED device.

Example 70

[0541] A block copolymer comprising poly(2-vinylpyridine) having amolecular weight of 83,000 and poly(methyl acrylate) having a molecularweight of 78,000, platinum particles coated with poly(2-vinylpyridine)and platinum particles coated with polymethyl acrylate are prepared.Then, 1 wt % of each of the polymer-coated platinum particles is addedto the block copolymer. The mixture is dissolved in THF to prepare a10-wt % solution. The solution is placed in a Teflon Petri dish to allowthe solvent to evaporate over 10 days. Further, drying is performed invacuum at 60° C. over 3 days, and thus a first film having a thicknessof 0.2 mm is provided.

[0542] Poly(2-vinylpyridine) having a molecular weight of 143,000 andplatinum particles covered with poly(2-vinylpyridine) are prepared.Then, 1 wt % of the polymer-coated platinum particles is added to thehomopolymer. The mixture is dissolved in THF to prepare a 10-wt %solution. The solution is placed in a Teflon Petri dish to allow thesolvent to evaporate over 10 days. Further, drying is performed invacuum at 60° C. for 3 days, thus a second film having a thickness of0.05 mm is provided.

[0543] Polymethyl acrylate having a molecular weight of 160,000 andplatinum particles covered with polymethyl acrylate are prepared. Then,1 wt % of the polymer-coated platinum particles is added to thehomopolymer. The mixture is dissolved in THF to prepare a 10-wt %solution. The solution is placed in a Teflon Petri dish to allow thesolvent to evaporate over 10 days. Further, drying is performed invacuum at 60° C. for 3 days, thus a third film having a thickness of0.05 mm is provided.

[0544] The second film, the first film and the third film are laminatedin this order and annealed in a nitrogen atmosphere at 160° C. for 40hours. Observation with TEM shows that a lamella structure is formed inthe first film. Further, these films are annealed at 240° C. for 10hours. Observation again with TEM shows that the polymer is fired andplatinum is made into a continuous product. Aluminum is deposited onboth sides of the structure to form electrodes. The structure is thencut into 1 cm×1 cm to manufacture a capacitor.

Example 71

[0545] A block copolymer comprising polystyrene (molecular weight:35,000) and polyethylene oxide (molecular weight: 70,000), and platinumparticles covered with the block copolymer are prepared. Then, 1 wt % ofthe polymer-coated platinum particles is added to the block copolymer.The mixture is dissolved in THF to prepare a 10% solution. The solutionis placed in a Teflon Petri dish to allow the solvent to evaporate over10 days. Further, drying is performed in vacuum at 60° C. for 3 days toprovide a film having a thickness of 0.05 mm. The film is annealed in anitrogen atmosphere at 140° C. for 40 hours. TEM observation shows thata cylindrical structure is formed in the film. Further, the film isannealed at 240° C. for 10 hours. When the film is observed by TEMagain, many pores 62 are formed in the polymer 61 as shown in FIG. 13,and many platinum particles 63 are adhered on the wall facing the pores62. The film is employed as a cathode catalytic layer of a fuel cell.

[0546] A block copolymer comprising polystyrene (molecular weight:35,000) and polyethylene oxide (molecular weight: 70,000), and platinumparticles covered with this block copolymer coating are prepared. Then,1 wt % of the polymer-coated ruthenium particles is added to the blockcopolymer. The mixture is dissolved in THF to prepare a 10-wt %solution. The solution is placed in a Teflon Petri dish to allow thesolvent to evaporate over 10 days. Further, drying in vacuum at 60° C.over 3 days provides a film having a thickness of 0.05 mm. The film isannealed in a nitrogen atmosphere at 140° C. for 40 hours. Observationwith TEM shows that a cylindrical structure appears in the film. Thefilm is annealed for 10 hours at 240° C. Observation again with TEMshows that a large number of pores are formed and a large number ofruthenium fine particles are adhered on the walls facing the pores, asshown in FIG. 13. The thin film is employed as a cathode catalytic layerof fuel cell.

[0547] A direct methanol fuel cell shown in FIG. 7 is manufactured.

[0548]FIG. 7 shows a conceptual diagram of a direct methanol fuel cell.The anode catalytic layer 11 and the cathode catalytic layer 14sandwiches the electrolyte film 16 made of a proton conductor. On theside of the anode catalytic layer 11, the fuel-evaporating layer 12 andthe fuel-permeating layer 13 are provided. On the side of the cathodecatalytic layer 14, the water-holding gas channel 14 is provided.

[0549] For the purpose of comparison, using a cathode catalytic layerhaving a structure that a platinum catalyst is buried in the matrix of afilm and a cathode catalytic layer having a structure that a rutheniumcatalyst is buried in the matrix of a film, a direct methanol fuel cellshown in FIG. 7 is manufactured.

[0550] The fuel cell of the present invention has higher powergeneration efficiency by at least twice as compared with the fuel cellof the comparative example.

What is claimed is:
 1. A method for manufacturing a porous structurecomprising: forming a molded product made of a pattern forming material;forming a structure having micro polymer phases in the molded product;and forming a porous structure by dry-etching the molded product toselectively remove a polymer phase from the structure having micropolymer phases; wherein the pattern forming material comprises acopolymer selected from the group consisting of: a block copolymer and agraft copolymer, each comprising two polymer chains whose ratio betweenN/(Nc−No) values of respective monomer units is 1.4 or more, where Nrepresents total number of atoms in the monomer unit, Nc represents thenumber of carbon atoms in the monomer unit, No represents the number ofoxygen atoms in the monomer unit; and a block copolymer and a graftcopolymer, each comprising a polysilane chain and a carbon-based organicpolymer chain.
 2. A method for forming a pattern comprising: forming afilm made of a pattern forming material on a substrate; forming astructure having micro polymer phases in the film; selectively removinga polymer phase from the structure having micro polymer phases formed inthe film by dry-etching; and transferring the pattern of the structurehaving micro polymer phases to the substrate by etching the substrateusing remaining another polymer phase in the film as a mask; wherein thepattern forming material comprises a copolymer selected from the groupconsisting of: a block copolymer and a graft copolymer, each comprisingtwo polymer chains whose ratio between N/(Nc−No) values of respectivemonomer units is 1.4 or more, where N represents total number of atomsin the monomer unit, Nc represents the number of carbon atoms in themonomer unit, No represents the number of oxygen atoms in the monomerunit; and a block copolymer and a graft copolymer, each comprising apolysilane chain and a carbon-based organic polymer chain.
 3. A methodfor forming a pattern comprising: forming a pattern transfer film on asubstrate; forming a film made of a pattern forming material comprisinga block copolymer or graft copolymer having two polymer chains whoseratio between dry etch rates is 1.3 or more, on the pattern transferfilm; forming a structure having micro polymer phases in the film;selectively removing a polymer phase from the structure having micropolymer phases formed in the film by dry etching; transferring thepattern of the structure having micro polymer phases to the patterntransfer film by etching the pattern transfer film using remaininganother polymer phase as a mask; and transferring the pattern of thestructure having micro polymer phases to the substrate by etching thesubstrate using the pattern transfer film as a mask in which thestructure having micro polymer phases is transferred.
 4. The methodaccording to claim 3, wherein a ratio of dry etch rates between thepattern transfer film and a polymer chain having a lowest dry etch rateamong the polymer chains constituting the block copolymer or graftcopolymer is 0.1 or more.
 5. The method according to claim 1, whereinthe block copolymer or graft copolymer comprises a polymer chaincontaining aromatic rings and an acrylic polymer chain.
 6. The methodaccording to claim 5, wherein the polymer chain containing aromaticrings is a polymer chain synthesized by polymerizing at least onemonomer selected from the group consisting of vinyl naphthalene, styreneand derivatives thereof, and the acrylic polymer chain is a polymerchain synthesized by polymerizing at least one monomer selected from thegroup consisting of acrylic acid, methacrylic acid, crotonic acid andderivatives thereof.
 7. The method according to claim 5, wherein theacrylic polymer chain has a molecular weight of 100,000 or less, andwherein the copolymer has a molecular weight distribution (Mw/Mn) of1.20 or less, and wherein a molecular weight ratio between the polymerchain containing aromatic rings and the acrylic polymer chain is rangingfrom 75:25 to 90:10.
 8. The method according to claim 5, wherein thecopolymer has a molecular weight of 50,000 or more and has a molecularweight distribution (Mw/Mn) of 1.15 or less, and wherein a molecularweight ratio between the polymer chain containing aromatic rings and theacrylic polymer chain is ranging from 75:25 to 90:10.
 9. A method formanufacturing a porous structure comprising: forming a molded productmade of a pattern forming material comprising a copolymer selected fromthe group consisting of a block copolymer and a graft copolymer eachhaving a polymer chain whose main chain is cut by irradiation with anenergy beam and an indecomposable polymer chain against irradiation withan energy beam; forming a structure having micro polymer phases in themolded product; cutting a main chain of a polymer phase in the structurehaving micro polymer phases by irradiating the molded product with anenergy beam; and forming a porous structure consisting of remaininganother polymer phase by selectively removing the polymer chain whosemain chain is cut by etching.
 10. The method according to claim 9,wherein the energy beam is selected from an electron beam, a γ-ray andan X-ray.
 11. A method for forming a pattern comprising: forming a filmmade of a pattern forming material comprising a copolymer selected fromthe group consisting of a block copolymer and a graft copolymer eachhaving a polymer chain whose main chain is cut by irradiation with anenergy beam and an indecomposable polymer chain against irradiation withan energy beam, on a substrate; forming a structure having micro polymerphases in the film; cutting the main chain of a polymer phase in thestructure having micro polymer phases by irradiating the film with anenergy beam; selectively removing the polymer chain whose main chain iscut from the structure having micro polymer phases by etching; andtransferring the pattern of the structure having micro polymer phases tothe substrate by etching the substrate using remaining another polymerphase as a mask.
 12. The method according to claim 11, furthercomprising: forming a pattern transfer film, on which the patternforming film is formed, on the substrate; transferring the pattern ofthe structure having micro polymer phases formed in the film made of apattern forming material to the pattern transfer film; and transferringthe pattern of the structure having micro polymer phases to thesubstrate by etching the substrate using the pattern transfer film towhich the pattern of the structure having micro polymer phases istransferred as a mask.
 13. The method according to claim 12, wherein aratio of etch rates between the pattern transfer film and a polymerchain having a lowest etch rate among polymer chains constituting theblock copolymer or graft copolymer is 0.1 or more.
 14. The methodaccording to claim 11, wherein the polymer chain whose main chain is cutby irradiation with an energy beam is a poly-alkylmethacrylate chain.15. The method according to claim 11, wherein the polymer chain whosemain chain is cut by irradiation with an energy beam has a molecularweight of 100,000 or less, and wherein the copolymer has a molecularweight distribution (Mw/Mn) of 1.20 or less, and wherein a molecularweight ratio between the indecomposable polymer chain and thedecomposable polymer chain is ranging from 75:25 to 90:10.
 16. Themethod according to claim 11, wherein the copolymer has a molecularweight of 50,000 or more and has a molecular weight distribution (Mw/Mn)of 1.15 or less, and wherein a molecular weight ratio between theindecomposable polymer chain and the decomposable polymer chain isranging from 75:25 to 90:10.
 17. The method according to claim 1,further comprising a metal element selected from the group consisting ofCr, V, Nb, Ti, Al, Mo, Li, Lu, Rh, Pb, Pt, Au and Ru.
 18. The methodaccording to claim 1, further comprising a plasticizer.
 19. The methodaccording to claim 1, further comprising an antioxidant or lightstabilizer.
 20. An electrochemical cell comprising a pair of electrodesand a separator interposed between the electrodes and impregnated withan electrolyte, wherein the separator has a porous structure formed byselectively removing a polymer phase from a block copolymer or graftcopolymer each having a structure having micro polymer phases.
 21. Theelectrochemical cell according to claim 20, wherein the porous structureconstituting the separator has an aggregated structure of domains, thedomain having a radius of gyration of 50 μm or less in which unit cellshaving a radius of gyration from 10 to 500 nm are periodically arranged.22. A hollow fiber filter made of a porous structure formed byselectively removing a polymer phase from a block copolymer or graftcopolymer each having a structure having micro polymer phases.
 23. Thehollow fiber filter according to claim 22, wherein the porous structurehas an aggregated structure of domains, the domain having a radius ofgyration of 50 μm or less in which unit cells having a radius ofgyration from 10 to 500 nm are periodically arranged.
 24. A method forforming a pattern comprising: forming a film made of a pattern formingmaterial on a substrate; forming a structure having micro polymer phasesin the film; removing a thermally decomposable polymer phase from thestructure having micro polymer phases by heating to a thermaldecomposition temperature or more; and transferring the pattern of thestructure having micro polymer phases to the substrate by etching thesubstrate using remaining another polymer phase in the film as a mask.25. The method according to claim 24, wherein the thermally decomposablepolymer is selected from the group consisting of a polyethylene oxideand a polypropylene oxide.
 26. The method according to claim 24, furthercomprising: forming a pattern transfer film, on which the film made of apattern forming material is formed, on the substrate; transferring thepattern of the structure having micro polymer phases formed in the filmto the pattern transfer film; and transferring the pattern of thestructure having micro polymer phases to the substrate by etching thesubstrate using the pattern transfer film to which the pattern of thestructure having micro polymer phases is transferred as a mask.
 27. Amethod for manufacturing a porous structure comprising: forming a moldedproduct made of a pattern forming material comprising a block copolymeror graft copolymer each having at least one thermally decomposablepolymer chain; forming a structure having micro polymer phases in themolded product; forming a porous structure having remaining anotherpolymer phase by removing the thermally decomposable polymer phase byheating to a thermal decomposition temperature or more; and fillingpores of the porous structure with an inorganic material.
 28. The methodaccording to claim 27, wherein the molded product of the pattern formingmaterial is a film formed on a substrate, and the structure having micropolymer phases is a sea-island structure or cylindrical structure, andwherein the pores of the porous structure are filled with the inorganicmaterial, followed by removing the porous structure to form a pattern ofthe inorganic material in a form of dots or filaments.
 29. The methodaccording to claim 27, wherein the block copolymer or graft copolymerconstituting the pattern forming material comprises a polymer chainselected from the group consisting of a polysilane chain, polysiloxanechain, a polyaclyronitrile derivative chain, a polyamic acid chain and apolyaniline derivative chain, and another polymer chain selected fromthe group consisting of a polyethylene oxide chain, a polypropyleneoxide chain, a polyacrylic acid derivative chain, a polymethacrylic acidderivative chain and a poly-α-methyl styrene chain.
 30. The methodaccording to claim 24, wherein the pattern forming material comprises ablock copolymer or graft copolymer comprising: a polymer chaincomprising a repeating unit represented by the following formula:

where R¹ and R² independently represent a substituted or unsubstitutedalkyl group, aryl group aralkyl group or alkoxyl group having 1 to 20carbon atoms; and a thermally decomposable polymer chain.
 31. Anelectrochemical cell comprising a pair of electrodes and an electrolytelayer interposed between the electrodes, wherein at least a part of theelectrodes have a porous structure formed by selectively removing apolymer phase from a block copolymer or graft copolymer having astructure having micro polymer phases.
 32. The electrochemical cellaccording to claim 31, wherein at least a part of the electrodes have aporous structure exhibiting a three-dimensional network structure andcomprising a continuous pore having correlation distances at both2{square root}{square root over (3)} times and 4 times a radius ofgyration of cross section of microdomains constituting thethree-dimensional network structure.
 33. The electrochemical cellaccording to claim 31, wherein at least a part of the electrodes have aporous carbon structure.
 34. A porous carbon structure having a porousstructure in which cylindrical pores having an average size from 0.1 to100 nm are arranged in a honeycomb manner.
 35. A method formanufacturing a porous carbon structure comprising: mixing a precursorof thermosetting resin, a surfactant, water and oil, thereby preparing amicroemulsion in which colloidal particles containing the precursor ofthermosetting resin are dispersed; curing the precursor of thermosettingresin unevenly distributed in the colloidal particles; removing thesurfactant, water and oil from the colloidal particles, therebyproviding porous structures of cured thermosetting resin; and firing tocarbonize the porous structures.
 36. A method for forming a patterncomprising: applying a blend of a polymer including a metal particle anda block copolymer or graft copolymer to a substrate to form a film;forming a structure having micro polymer phases in the film andsegregating the metal particles covered with the polymer in a centralportion of a polymer phase or at an interface between the polymer phasesin the block copolymer or the graft copolymer; leaving the metalparticles by selectively or entirely removing the polymer phases byetching in which the metal particles are segregated.
 37. A method formanufacturing a magnetic recording medium comprising: leaving metalparticles on a substrate by the method according to claim 36; anddepositing a magnetic material on the metal particles.
 38. A method formanufacturing a field emission display comprising: leaving metalparticles on a substrate by the method according to claim 36; andforming emitters by depositing a conductor or semiconductor on the metalparticles.
 39. A method for manufacturing a capacitor comprising:forming a film made of a blend of a polymer including a metal particleand a block copolymer or graft copolymer; allowing the film to form alamella structure having micro polymer phases and segregating the metalparticles covered with the polymer in a central portion of each polymerphase in the lamella structure; and aggregating the metal particles toform a metal layer in the central portion of each polymer phase in thelamella structure.
 40. A method for manufacturing a catalytic layer of afuel cell comprising: forming a film made of a blend of a blockcopolymer or graft copolymer including a metal particle and a blockcopolymer or graft copolymer; forming a structure having micro polymerphases in the film and segregating the metal particles covered with thepolymer at an interface between the polymer phases forming the structurehaving micro polymer phases; and leaving the metal particles on asurface of remaining another polymer phase by selectively removing apolymer phase in the structure having micro polymer phases.